Bump library version to v1.1.0

[duckontheweb]

Updates library version and CHANGELOG for a v1.1.0 release.

PR Checklist:

• Code is formatted (run pre-commit run --all-files)
• Tests pass (run scripts/test)
• Documentation has been updated to reflect changes, if applicable
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[codecov-commenter]

Codecov Report

Merging #583 (b872d9c) into main (3a1dde6) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #583   +/-   ##
=======================================
  Coverage   94.69%   94.69%           
=======================================
  Files          75       75           
  Lines       10776    10776           
  Branches     1053     1053           
=======================================
  Hits        10204    10204           
  Misses        396      396           
  Partials      176      176           

Impacted Files	Coverage Δ
pystac/version.py	100.00% <100.00%> (ø)

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