Reduce frequency of dependabot autoupdates to quarterly (matching pre-commit) - #1415

Description

Dependabot autoupdates don't seem to me to be worth doing monthly.

"Ready for review" checklist

• Place this Pull Request (PR) in draft until it is ready for review (see below)
• Please review our Pull Request Guide
• Mark "ready for review" after following instructions in the guide

Merge checklist

• PR title is descriptive
• PR body contains links to related and resolved issues (e.g. closes #1)
• If needed, CHANGELOG.md updated
• If needed, docs and/or README.md updated
• If needed, unit tests added (unsure how? see below!)
• All checks passing (tip: comment pre-commit.ci autofix if pre-commit is failing)
• At least one approval

Need help? We welcome contributions at every experience level. You don't have to
write tests alone — open your PR and ask for help. It's also fine to let GitHub run tests
for you, via Continuous Integration (CI),
instead of running them locally. If anything fails and you're not sure why, just
mention @earthaccess-dev/maintainers in a comment and we'll work with you!

📚 Documentation preview 📚: https://earthaccess--1415.org.readthedocs.build/en/1415/