Fix reportInvalidTypeForm diagnostics in sympy-stubs

[debonte]

Fix Variable not allowed in type expression issues in sympy-stubs. I guess this is a recent fix/behavior change in Pyright.

/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/algebraicfield.pyi:18:31 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/algebraicfield.pyi:43:79 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/expressiondomain.pyi:50:32 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/integerring.pyi:16:14 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/integerring.pyi:28:28 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/old_fractionfield.pyi:14:31 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/old_fractionfield.pyi:36:31 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/old_polynomialring.pyi:53:25 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/rationalfield.pyi:[22](https://github.com/microsoft/python-type-stubs/actions/runs/14805952987/job/41674194643?pr=361#step:6:23):14 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/rationalfield.pyi:39:28 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
/home/runner/work/python-type-stubs/python-type-stubs/stubs/sympy-stubs/polys/domains/rationalfield.pyi:40:61 - error: Variable not allowed in type expression (reportInvalidTypeForm)
Error: Variable not allowed in type expression (reportInvalidTypeForm)
11 errors, 0 warnings, 0 informations
Error: 11 errors

[Avasam]

Looks like I duplicated this in #367.
I think the dtype attributes should be kept though, just not used as type aliases