Fix: Disallow inheriting from tuples and functions

[JSAbrahams]

Summary

In Mamba source, we now disallow inheriting from tuples and functions, so

class Foo(a: Int): (Int, Str)

and

class Foo(a: Int): (Int) -> Int

are no longer allowed.

Added Tests

• To test that we cannot inherit from tuples and functions
• Small test to verify we don't allow unrecognised character @

[codecov]

Codecov Report

❌ Patch coverage is 92.96875% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.50%. Comparing base (ff415db) to head (3317b88).

Files with missing lines	Patch %	Lines
src/main.rs	0.00%	8 Missing ⚠️
src/check/context/field/python.rs	97.43%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #494      +/-   ##
===========================================
+ Coverage    91.28%   92.50%   +1.22%     
===========================================
  Files          113      113              
  Lines        15598    15709     +111     
===========================================
+ Hits         14238    14531     +293     
+ Misses        1360     1178     -182     

Files with missing lines	Coverage Δ
src/check/context/parent/generic.rs	83.33% <100.00%> (+8.33%)	⬆️
src/check/mod.rs	86.79% <100.00%> (+18.27%)	⬆️
src/check/name/mod.rs	97.56% <100.00%> (+3.03%)	⬆️
src/check/name/string_name/mod.rs	90.90% <100.00%> (+9.74%)	⬆️
src/lib.rs	85.15% <100.00%> (+3.33%)	⬆️
src/check/context/field/python.rs	90.62% <97.43%> (+37.99%)	⬆️
src/main.rs	0.00% <0.00%> (ø)

... and 9 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.