Update Rascal Maven to 0.30.6

[toinehartman]

Update the Rascal Maven plugin as required by #2602. Should resolve failure of PR usethesource/rascal-language-servers#957.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46%. Comparing base (beb7c30) to head (82f823d).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##              main   #2608   +/-   ##
=======================================
  Coverage       46%     46%           
+ Complexity    6653    6652    -1     
=======================================
  Files          793     793           
  Lines        65697   65697           
  Branches      9839    9839           
=======================================
+ Hits         30600   30616   +16     
+ Misses       32732   32720   -12     
+ Partials      2365    2361    -4     

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