Use buf-action in CI

This updates CI to use the new `buf-action` replacing `buf-setup`,
`buf-lint`, `buf-breaking` and `buf-push` unifying these tasks as one.
The new behaviour is as follows:
- On pull_requests: run lint, format and breaking change detection
  checks.
- On push to main: push the changes of the latest commit with the label
  of the current branch (main).

The following changes were made to support the new aciton:
- The file `.bufversion` at the repository root now controls the version.
  This is read by both the Makefile and the action to fetch the correct
  version of buf.
- Checks no longer block pushes of commits to the BSR.
- Formatting checks have been added to `buf-ci.yaml`.

.bufversion

@@ -0,0 +1 @@
+1.32.2

.github/workflows/buf-ci.yaml

@@ -0,0 +1,18 @@
+name: buf
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+permissions:
+  contents: read
+  pull-requests: write
+jobs:
+  buf:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: bufbuild/[email protected]
+        with:
+          token: ${{ secrets.BUF_TOKEN }}

.github/workflows/ci.yaml

@@ -12,12 +12,13 @@ jobs:
       - name: install
         uses: actions/setup-go@v5
         with:
-          go-version: 1.21.x
+          go-version: 1.22.x
+          cache: false
       - name: cache
         uses: actions/cache@v4
         with:
           path: ~/go/pkg/mod
-          key: ${{ runner.os }}-registry-proto-ci-${{ hashFiles('**/Makefile') }}
+          key: ${{ runner.os }}-registry-proto-ci-${{ hashFiles('.bufversion') }}
           restore-keys: ${{ runner.os }}-registry-proto-ci-
       - name: make
         run: make

Makefile

@@ -10,7 +10,7 @@ BIN := .tmp/bin
 export PATH := $(BIN):$(PATH)
 export GOBIN := $(abspath $(BIN))
 
-BUF_VERSION := v1.32.0-beta.1
+BUF_VERSION ?= $(shell cat .bufversion)
 COPYRIGHT_YEARS := 2023-2024
 
 .PHONY: help
@@ -56,8 +56,8 @@ checkgenerate:
 
 $(BIN)/buf: Makefile
 	@mkdir -p $(@D)
-	go install github.com/bufbuild/buf/cmd/buf@$(BUF_VERSION)
+	go install github.com/bufbuild/buf/cmd/buf@v$(BUF_VERSION)
 
 $(BIN)/license-header: Makefile
 	@mkdir -p $(@D)
-	go install github.com/bufbuild/buf/private/pkg/licenseheader/cmd/license-header@$(BUF_VERSION)
+	go install github.com/bufbuild/buf/private/pkg/licenseheader/cmd/license-header@v$(BUF_VERSION)