chore: release spanner 1.13.0 (#3423)

Co-authored-by: Thiago Nunes <thiagotnunes@google.com>
diff --git a/spanner/CHANGES.md b/spanner/CHANGES.md
index 71f3c38..b226c91 100644
--- a/spanner/CHANGES.md
+++ b/spanner/CHANGES.md
@@ -1,5 +1,32 @@
 # Changes
 
+## [1.13.0](https://www.github.com/googleapis/google-cloud-go/compare/spanner/v1.12.0...v1.13.0) (2021-01-15)
+
+
+### Features
+
+* **spanner/spannertest:** implement ANY_VALUE aggregation function ([#3428](https://www.github.com/googleapis/google-cloud-go/issues/3428)) ([e16c3e9](https://www.github.com/googleapis/google-cloud-go/commit/e16c3e9b412762b85483f3831ee586a5e6631313))
+* **spanner/spannertest:** implement FULL JOIN ([#3218](https://www.github.com/googleapis/google-cloud-go/issues/3218)) ([99f7212](https://www.github.com/googleapis/google-cloud-go/commit/99f7212bd70bb333c1aa1c7a57348b4dfd80d31b))
+* **spanner/spannertest:** implement SELECT ... FROM UNNEST(...) ([#3431](https://www.github.com/googleapis/google-cloud-go/issues/3431)) ([deb466f](https://www.github.com/googleapis/google-cloud-go/commit/deb466f497a1e6df78fcad57c3b90b1a4ccd93b4))
+* **spanner/spannertest:** support array literals ([#3438](https://www.github.com/googleapis/google-cloud-go/issues/3438)) ([69e0110](https://www.github.com/googleapis/google-cloud-go/commit/69e0110f4977035cd1a705c3034c3ba96cadf36f))
+* **spanner/spannertest:** support AVG aggregation function ([#3286](https://www.github.com/googleapis/google-cloud-go/issues/3286)) ([4788415](https://www.github.com/googleapis/google-cloud-go/commit/4788415c908f58c1cc08c951f1a7f17cdaf35aa2))
+* **spanner/spannertest:** support Not Null constraint ([#3491](https://www.github.com/googleapis/google-cloud-go/issues/3491)) ([c36aa07](https://www.github.com/googleapis/google-cloud-go/commit/c36aa0785e798b9339d540e691850ca3c474a288))
+* **spanner/spannertest:** support UPDATE DML ([#3201](https://www.github.com/googleapis/google-cloud-go/issues/3201)) ([1dec6f6](https://www.github.com/googleapis/google-cloud-go/commit/1dec6f6a31768a3f70bfec7274828301c22ea10b))
+* **spanner/spansql:** define structures and parse UPDATE DML statements ([#3192](https://www.github.com/googleapis/google-cloud-go/issues/3192)) ([23b6904](https://www.github.com/googleapis/google-cloud-go/commit/23b69042c58489df512703259f54d075ba0c0722))
+* **spanner/spansql:** support DATE and TIMESTAMP literals ([#3557](https://www.github.com/googleapis/google-cloud-go/issues/3557)) ([1961930](https://www.github.com/googleapis/google-cloud-go/commit/196193034a15f84dc3d3c27901990e8be77fca85))
+* **spanner/spansql:** support for parsing generated columns ([#3373](https://www.github.com/googleapis/google-cloud-go/issues/3373)) ([9b1d06f](https://www.github.com/googleapis/google-cloud-go/commit/9b1d06fc90a4c07899c641a893dba0b47a1cead9))
+* **spanner/spansql:** support NUMERIC data type ([#3411](https://www.github.com/googleapis/google-cloud-go/issues/3411)) ([1bc65d9](https://www.github.com/googleapis/google-cloud-go/commit/1bc65d9124ba22db5bec4c71b6378c27dfc04724))
+* **spanner:** Add a DirectPath fallback integration test ([#3487](https://www.github.com/googleapis/google-cloud-go/issues/3487)) ([de821c5](https://www.github.com/googleapis/google-cloud-go/commit/de821c59fb81e9946216d205162b59de8b5ce71c))
+* **spanner:** attempt DirectPath by default ([#3516](https://www.github.com/googleapis/google-cloud-go/issues/3516)) ([bbc61ed](https://www.github.com/googleapis/google-cloud-go/commit/bbc61ed368453b28aaf5bed627ca2499a3591f63))
+* **spanner:** include User agent ([#3465](https://www.github.com/googleapis/google-cloud-go/issues/3465)) ([4e1ef1b](https://www.github.com/googleapis/google-cloud-go/commit/4e1ef1b3fb536ef950249cdee02cc0b6c2b56e86))
+* **spanner:** run E2E test over DirectPath ([#3466](https://www.github.com/googleapis/google-cloud-go/issues/3466)) ([18e3a4f](https://www.github.com/googleapis/google-cloud-go/commit/18e3a4fe2a0c59c6295db2d85c7893ac51688083))
+* **spanner:** support NUMERIC in mutations ([#3328](https://www.github.com/googleapis/google-cloud-go/issues/3328)) ([fa90737](https://www.github.com/googleapis/google-cloud-go/commit/fa90737a2adbe0cefbaba4aa1046a6efbba2a0e9))
+
+
+### Bug Fixes
+
+* **spanner:** fix session leak ([#3461](https://www.github.com/googleapis/google-cloud-go/issues/3461)) ([11fb917](https://www.github.com/googleapis/google-cloud-go/commit/11fb91711db5b941995737980cef7b48b611fefd)), refs [#3460](https://www.github.com/googleapis/google-cloud-go/issues/3460)
+
 ## [1.12.0](https://www.github.com/googleapis/google-cloud-go/compare/spanner/v1.11.0...v1.12.0) (2020-11-10)