Use 1.21 in dependabot workflow

Signed-off-by: Danil Grigorev <[email protected]>

.github/workflows/pr-dependabot.yaml

@@ -26,7 +26,8 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # tag=v5.0.0
       with:
-        go-version: ${{ steps.vars.outputs.go_version }}
+        # go-version: ${{ steps.vars.outputs.go_version }} // TODO: we have to use go version consistent with test infra jobs
+        go-version: '1.21'
     - uses: actions/cache@ab5e6d0c87105b4c9c2047343972218f562e4319 # tag=v4.0.1
       name: Restore go cache
       with: