fix(ci): update the Buf CI to push tags to the Buf Schema Registry (#280

)

This PR fixes the push of a new tag to BSR. 

Tested in my fork in here: https://buf.build/chamirachid/nmt/labels


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Introduced a new GitHub Actions workflow for continuous integration of
Buf-related changes.
- Added a workflow for automating the release of protobuf definitions to
the Buf Schema Registry.
	- New script for downloading the specified version of the `buf` binary.

- **Bug Fixes**
	- Removed the outdated `buf-ci` workflow to streamline processes.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.github/workflows/buf-ci.yml

@@ -0,0 +1,22 @@
+name: buf-ci
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+permissions:
+  contents: read
+  pull-requests: write
+jobs:
+  buf:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: bufbuild/buf-setup-action@v1
+      - uses: bufbuild/buf-breaking-action@v1
+        with:
+          input: pb
+          against: 'https://github.com/celestiaorg/nmt.git#branch=main,subdir=pb'
+      - uses: bufbuild/buf-lint-action@v1
+        with:
+          input: pb

.github/workflows/buf-release.yml

@@ -0,0 +1,23 @@
+name: buf-release
+on:
+  push:
+    tags:
+      - "v*"
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: bufbuild/buf-setup-action@v1
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          version: "1.44.0"
+      # Push the protobuf definitions to the BSR
+      - uses: bufbuild/buf-push-action@v1
+        with:
+          buf_token: ${{ secrets.BUF_TOKEN }}
+      - name: "push the tag label to BSR"
+        run: |
+          set -euo pipefail
+          echo ${{ secrets.BUF_TOKEN }} | buf registry login --token-stdin
+          buf push --label ${{ github.ref_name }}