Workflow to verify the OSX latest version (#129)

Workflow triggers when a push is made to main branch which is common with a version update. Installs Besu on OSX runner
and check the installed version is same as the version configured in besu.rb file. This verifies that published
version is the latest version installed on OSX using Homebrew

Signed-off-by: Chaminda Divitotawela <cdivitotawela@gmail.com>

.github/workflows/verify.yml

@@ -0,0 +1,47 @@
+# This workflow install the Besu using homebrew and verify that installed version is the latest published version
+# This does NOT test running Besu in OSX
+# This is commonly used when the Besu version is updated and to verify the updated version can be installed 
+# on OSX using homebrew
+name: Verify
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  verify:
+    runs-on: macos-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
+
+      - name: Install Besu
+        run: |
+          brew tap hyperledger/besu
+          brew install besu
+
+      - name: Verify Besu installed
+        run: |
+          brew list | grep besu || {
+            echo "ERROR: Could not find besu installed"
+            exit 1
+          }
+      
+      - name: Verify Besu version
+        run: |
+          LATEST_VERSION=$(grep url besu.rb | sed 's|.*download/\([^/]*\).*|\1|g')
+          
+          # Could not grep the line using 'besu:'' with GitHub runner
+          # So using the 'stable' word in grep which seems to appear only in the line required
+          INSTALLED_VERSION=$(brew info besu | grep 'stable' | sed 's|.* stable \([0-9]*\.[0-9]*\.[0-9]*\).*|\1|g')
+
+          if [[ "$LATEST_VERSION" == "$INSTALLED_VERSION" ]]
+          then
+            echo "Latest version [$LATEST_VERSION] match installed version [$INSTALLED_VERSION]"
+            exit 0
+          else
+            echo "ERROR: Latest version [$LATEST_VERSION] does not match installed version [$INSTALLED_VERSION]"
+            exit 1
+          fi
+