fix(examples): migrate imports to charm.land for the glamour example

[mhdna]

If you try to go mod tidy the required packages for the glamour example (out of all the other examples), you'll be presented with the error message: module declares its path as: charm.land/glamour/v2 but was required as: github.com/charmbracelet/glamour/v2, since the glamour package initializes it's module name as charm.land/glamour/v2.

• I have read CONTRIBUTING.md.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.09%. Comparing base (65c3978) to head (742ced6).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1642   +/-   ##
=======================================
  Coverage   56.09%   56.09%           
=======================================
  Files          25       25           
  Lines        1287     1287           
=======================================
  Hits          722      722           
  Misses        481      481           
  Partials       84       84           

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[andreynering]

Thank you!