Add LSST filters

[mkelley]

>>> from sbpy.photometry import bandpass
>>> u = bandpass("LSST u")
>>> u.avgwave()
<Quantity 3723.54596825 Angstrom>

[github-actions]

Thank you for your contribution to sbpy, an Astropy affiliated package! 🌌 This checklist is meant to remind the package maintainers who will review this pull request of some common things to look for.

• Do the proposed changes actually accomplish desired goals?
• Do the proposed changes follow the sbpy coding guidelines?
• Are tests added/updated as required? If so, do they follow the Astropy testing guidelines?
• Are docs added/updated as required? If so, do they follow the Astropy documentation guidelines?
• Is rebase and/or squash necessary? If so, please provide the author with appropriate instructions. Also see instructions for rebase and squash.
• Did the CI pass? If no, are the failures related?
• Is a change log needed? If yes, did the change log check pass? If no, add the "no-changelog-entry-needed" label.
• Is a milestone added?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.72%. Comparing base (843b1a2) to head (7d63b16).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #431   +/-   ##
=======================================
  Coverage   84.72%   84.72%           
=======================================
  Files          92       92           
  Lines        8459     8460    +1     
=======================================
+ Hits         7167     7168    +1     
  Misses       1292     1292           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[mkelley]

Looks like MacOS tests will continue to fail until #427 is done.