automate release for cocoapods via github actions

.github/workflows/publish-to-cocoapods.yml

@@ -0,0 +1,26 @@
+name: publish-to-cocoapods
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  build:
+    runs-on: macos-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: true
+
+      - name: Install Cocoapods
+        run: gem install cocoapods
+
+      - name: Publish to Cocoapods registry
+        run: |
+          set -eo pipefail
+          pod lib lint --allow-warnings
+          pod trunk push --allow-warnings
+        env:
+          COCOAPODS_TRUNK_TOKEN: ${{ secrets.COCOAPODS_TRUNK_TOKEN }}
+          RELEASE_VERSION: ${{ github.event.release.tag_name }}

GRMustache.swift.podspec

@@ -1,6 +1,9 @@
+version = ENV["RELEASE_VERSION"]
+exit 1 if version.to_s.empty?
+
 Pod::Spec.new do |s|
 	s.name     = 'GRMustache.swift'
-	s.version  = '5.0.1'
+	s.version  = version
 	s.license  = { :type => 'MIT', :file => 'LICENSE' }
 	s.summary  = 'Flexible Mustache templates for Swift.'
 	s.homepage = 'https://github.com/groue/GRMustache.swift'