Remove parallel3 workflow (runner-03 proven)

.gitea/workflows/parallel3.yaml

@@ -1,18 +0,0 @@
-name: parallel3
-on: [push]
-jobs:
-  job-a:
-    runs-on: host
-    steps:
-      - name: sleep-a
-        run: sleep 20; echo "job-a done"
-  job-b:
-    runs-on: host
-    steps:
-      - name: sleep-b
-        run: sleep 20; echo "job-b done"
-  job-c:
-    runs-on: host
-    steps:
-      - name: sleep-c
-        run: sleep 20; echo "job-c done"