[docs] pin to use Julia v1.11

[odow]

Fix the Julia version to 1.11 for compatibility with Enzyme.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.86%. Comparing base (d3e517d) to head (d1e7d58).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4083   +/-   ##
=======================================
  Coverage   99.86%   99.86%           
=======================================
  Files          43       43           
  Lines        5910     5910           
=======================================
  Hits         5902     5902           
  Misses          8        8           

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