ads-github-merge-all-upstreams: default invocation too chatty with "no upstream changes to merge" message

[salewski]

The default output of the 'ads-github-merge-all-upstreams' program (that is,
when the program is invoked with no command line options) is too chatty; it is
emitting a bunch of "no upstream changes to merge" messages:

...
ads-github-merge-all-upstreams (info): [repo: "foo"] no upstream changes to merge, and "aggressive push" (a al '-p -p') not specified; skipping (okay)
ads-github-merge-all-upstreams (info): [repo: "bar"] no upstream changes to merge, and "aggressive push" (a al '-p -p') not specified; skipping (okay)
ads-github-merge-all-upstreams (info): [repo: "baz"] no upstream changes to merge, and "aggressive push" (a al '-p -p') not specified; skipping (okay)
...

Probably just a missing mode guard check...