Add auto-tag workflow (#110)

* Add auto-tag workflow
Runs when the version is bumped, creates and pushes a tag.

Author: StanFromIreland

.github/workflows/auto-tag.yml

@@ -0,0 +1,40 @@
+name: Auto Tag on Version Bump
+
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - VERSION
+
+jobs:
+  tag-repo:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v5
+
+      - name: Get current version
+        id: version
+        run: |
+          VERSION=$(cat VERSION)
+          echo "version=$VERSION" >> $GITHUB_OUTPUT
+
+      - name: Check if tag already exists
+        id: checktag
+        run: |
+          if git rev-parse "v${{ steps.version.outputs.version }}" >/dev/null 2>&1; then
+            echo "skip=true" >> $GITHUB_OUTPUT
+          else
+            echo "skip=false" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Push tag
+        if: steps.checktag.outputs.skip == 'false'
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git tag "v${{ steps.version.outputs.version }}"
+          git push origin "v${{ steps.version.outputs.version }}"