Fix CI errors: linting, type checking, and tests

- Fix import sorting in test_instruments.py (ruff I001)
- Install pandas-stubs for mypy type checking
- Add garbage collection cleanup to repository test fixtures
- Prevent Windows file locking errors in tempfile cleanup

All CI checks now passing: lint, type check, and all 244 tests.

tests/unit/test_instruments.py

@@ -8,11 +8,11 @@ import pytest
 
 from py_dvt_ate.instruments import (
     IMultimeter,
-    IPowerSupply,
-    IThermalChamber,
     InstrumentConfig,
     InstrumentFactory,
     InstrumentSet,
+    IPowerSupply,
+    IThermalChamber,
 )
 from py_dvt_ate.instruments.drivers import (
     MultimeterDriver,