ci: add buf lints to generated file checks

Signed-off-by: William Findlay <[email protected]>

.github/workflows/generated-files.yaml

@@ -5,12 +5,20 @@ on:
       - main
       - v*
     paths-ignore:
-      - 'docs/**'
+      - "docs/**"
   pull_request:
     paths-ignore:
-      - 'docs/**'
+      - "docs/**"
 
 jobs:
+  checks:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+      - uses: bufbuild/buf-action@v1
+        with:
+          breaking_against: ".git#branch=origin/main,subdir=api/v1"
+          exclude_paths: "vendor"
   generated-files:
     runs-on: ubuntu-latest
     steps:
@@ -19,7 +27,7 @@ jobs:
         uses: actions/setup-go@3041bf56c941b39c61721a86cd11f3bb1338122a # v5.2.0
         with:
           # renovate: datasource=golang-version depName=go
-          go-version: '1.23.5'
+          go-version: "1.23.5"
       - name: Go version
         run: go version
       - name: Validate that generated files are up to date.