chore: add release-please automation

Adds release-please workflow + config so that merged PRs with
conventional commits trigger automated changelog updates and release PRs.
Manifest seeds at v0.1.0 (already released).

Signed-off-by: Erik Nilsen <enilsen16@live.com>

Author: enilsen16

.github/workflows/release-please.yml

@@ -0,0 +1,19 @@
+name: release-please
+
+on:
+  push:
+    branches: [main]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  release-please:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: googleapis/release-please-action@v4
+        id: release
+        with:
+          config-file: .release-please-config.json
+          manifest-file: .release-please-manifest.json

.release-please-config.json

@@ -0,0 +1,12 @@
+{
+  "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json",
+  "release-type": "simple",
+  "changelog-path": "CHANGELOG.md",
+  "bump-minor-pre-major": true,
+  "bump-patch-for-minor-pre-major": true,
+  "packages": {
+    ".": {
+      "package-name": "protobuf-pony"
+    }
+  }
+}

.release-please-manifest.json

@@ -0,0 +1,3 @@
+{
+  ".": "0.1.0"
+}