Add a manually-triggered test action

.forgejo/workflows/manual.yml

@@ -0,0 +1,15 @@
+# This file needs to be manually run
+
+name: Manual Test
+
+on:
+    workflow_dispatch:
+
+jobs:
+  ls:
+    name: List
+    runs-on: docker
+    steps:
+      uses: https://forge.niblock.tech/actions/checkout@v4
+      run: |
+        ls ${{ github.workspace }}