Try to upgrade Bazel harder on Windows.

Change-Id: I22ad66dc3ebd4f4bf95605e114d07bea3f67d6eb
Reviewed-on: https://code-review.googlesource.com/c/re2/+/44216
Reviewed-by: Paul Wankadia <junyer@google.com>
diff --git a/kokoro/bazel.sh b/kokoro/bazel.sh
index 7437ef3..9c79ca8 100755
--- a/kokoro/bazel.sh
+++ b/kokoro/bazel.sh
@@ -5,7 +5,7 @@
 
 case "${KOKORO_JOB_NAME}" in
   */windows-*)
-    choco upgrade bazel -y
+    choco upgrade bazel -y -f
     ;;
   *)
     # Use the script provided by Kokoro.