Reduce Dependabot frequency for Python dependencies (#2069)

From weekly to monthly, to reduce toil and match the frequency used for other dependencies - now that uv is more mature and we no longer need to keep as rapidly up to date.

We can still trigger manual Dependabot runs as needed (and GitHub will continue to open out-of-schedule PRs for any security updates if needed).

GUS-W-21870812.

Signed-off-by: Ed Morley <501702+edmorley@users.noreply.github.com>

Author: edmorley

.github/dependabot.yml

@@ -32,9 +32,7 @@ updates:
   - package-ecosystem: "pip"
     directory: "/"
     schedule:
-      # We set this to a more frequent interval than the above since uv is still under rapid
-      # iteration, and we'll generally want to be on a recent (if not the latest) version.
-      interval: "weekly"
+      interval: "monthly"
     ignore:
       # We're not updating to setuptools v71+ due to its new approach to vendored dependencies:
       # https://github.com/heroku/heroku-buildpack-python/pull/1630#issuecomment-2324236653