Add release branch 37.x

PiperOrigin-RevId: 1000335874

.github/workflows/test_release_branches.yml

diff --git a/.github/workflows/test_release_branches.yml b/.github/workflows/test_release_branches.yml
index d081d17..e9cfb35 100644
--- a/.github/workflows/test_release_branches.yml
+++ b/.github/workflows/test_release_branches.yml
@@ -13,7 +13,7 @@
     strategy:
       fail-fast: false
       matrix:
-        branch: [25.x, 33.x, 36.x]
+        branch: [25.x, 33.x, 36.x. 37.x]
     runs-on: ubuntu-latest
     permissions:
       actions: write