configure publishing automation (dart-archive/source_maps#74)

* configure publishing automation

* update changelog

Author: devoncarew

pkgs/source_maps/.github/workflows/publish.yaml

@@ -0,0 +1,14 @@
+# A CI configuration to auto-publish pub packages.
+
+name: Publish
+
+on:
+  pull_request:
+    branches: [ master ]
+  push:
+    tags: [ 'v[0-9]+.[0-9]+.[0-9]+*' ]
+
+jobs:
+  publish:
+    if: ${{ github.repository_owner == 'dart-lang' }}
+    uses: dart-lang/ecosystem/.github/workflows/publish.yaml@main

pkgs/source_maps/CHANGELOG.md

@@ -1,8 +1,8 @@
-# 0.10.12
+## 0.10.12
 
 * Add additional types at API boundaries.
 
-# 0.10.11
+## 0.10.11
 
 * Populate the pubspec `repository` field.
 * Update the source map documentation link in the readme.