Require GAP 4.11

[wilfwilson]

Since the CI tests against GAP stable-4.10 are failing (I think it's related to the CI cloning the orb package, which itself requires GAP 4.12). And anyway, stable-4.11 is itself pretty old now, so it seems fair enough.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.09%. Comparing base (a0258d6) to head (0e7435f).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #49   +/-   ##
=======================================
  Coverage   62.09%   62.09%           
=======================================
  Files           3        3           
  Lines         153      153           
=======================================
  Hits           95       95           
  Misses         58       58           

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[james-d-mitchell]

Thanks @wilfwilson looks good to me!