chore: update latest Go runtime to 1.20

diff --git a/.github/renovate.json b/.github/renovate.json
index bf5f2f5..391f4df 100644
--- a/.github/renovate.json
+++ b/.github/renovate.json

@@ -20,7 +20,7 @@
     ],
     "force": {
         "constraints": {
-            "go": "1.19"
+            "go": "1.20"
         }
     }
 }

diff --git a/.github/workflows/vet.yml b/.github/workflows/vet.yml
index 63147b5..3c0ac35 100644
--- a/.github/workflows/vet.yml
+++ b/.github/workflows/vet.yml

@@ -16,7 +16,7 @@
     - uses: actions/checkout@v3
     - uses: actions/setup-go@v3
       with:
-        go-version: '1.19'
+        go-version: '1.20'
     - name: Install tools
       run: |
         go install golang.org/x/lint/golint@latest && \

diff --git a/internal/gapicgen/cmd/genbot/Dockerfile b/internal/gapicgen/cmd/genbot/Dockerfile
index 8ad0b83..f7aa89d 100644
--- a/internal/gapicgen/cmd/genbot/Dockerfile
+++ b/internal/gapicgen/cmd/genbot/Dockerfile

@@ -19,7 +19,7 @@
 RUN protoc --version
 
 # Install Go...quietly.
-RUN wget -O /tmp/go.tgz https://dl.google.com/go/go1.19.linux-amd64.tar.gz -q && \
+RUN wget -O /tmp/go.tgz https://dl.google.com/go/go1.20.linux-amd64.tar.gz -q && \
     tar -C /usr/local -xzf /tmp/go.tgz && \
     rm /tmp/go.tgz
 ENV PATH /usr/local/go/bin:$PATH

diff --git a/internal/gapicgen/go.mod b/internal/gapicgen/go.mod
index 5381848..ceb0627 100644
--- a/internal/gapicgen/go.mod
+++ b/internal/gapicgen/go.mod

@@ -1,6 +1,6 @@
 module cloud.google.com/go/internal/gapicgen
 
-go 1.19
+go 1.20
 
 require (
 	cloud.google.com/go/internal/aliasfix v0.0.0

diff --git a/internal/postprocessor/Dockerfile b/internal/postprocessor/Dockerfile
index ce02abc..75e6420 100644
--- a/internal/postprocessor/Dockerfile
+++ b/internal/postprocessor/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM golang:1.19 as builder
+FROM golang:1.20 as builder
 
 # Copy local code to the container image.
 COPY . /internal/