Build: Remove spider-check trigger from new branches/tags

The `paths` filter isn't just about commits that add or modify files,
GitHub seemingly also triggers this for any new tags and new branches
that inherit from existing commits/branches where these files already
exist, even if the new branch/tag does not add or modify these files
at all.

This seems like a bug, but is sufficiently annoying (especially on
older 2.x-related branches) that it's better to turn off in favour
of manual workflow_dispatch for the rare case where I want to test
this before a given commit is merged to main.

.github/workflows/spider-check.yaml

@@ -5,13 +5,6 @@ on:
     - cron: '0 0 * * 5'
   # Or manually
   workflow_dispatch:
-  # Or when developing this workflow
-  push:
-    paths:
-      - .github/workflows/spider-check.yaml
-  pull_request:
-    paths:
-      - .github/workflows/spider-check.yaml
 
 jobs:
   spider-check: