Implement automatic PR updates (#529)

* Implement automatic PR update

* [pre-commit.ci lite] apply automatic fixes

---------

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

Author: MattyTheHacker

.github/workflows/pr-auto-updater.yaml

@@ -0,0 +1,19 @@
+name: pr-auto-update
+on:
+    push: {}
+
+jobs:
+    pr-auto-update:
+        name: Automatic PR Updater
+        runs-on: ubuntu-latest
+        permissions:
+            pull-requests: write
+            contents: write
+        steps:
+            - uses: CSSUoB/[email protected]
+              env:
+                GITHUB_TOKEN: '${{ secrets.PR_AUTO_UPDATE_TOKEN }}'
+                PR_FILTER: 'labelled'
+                PR_LABELS: 'sync'
+                MERGE_CONFLICT_ACTION: 'label'
+                MERGE_CONFLICT_LABEL: 'conflict'