fix: update minimum pytest version to 6.2.0

The previous minimum version (pytest>=3.6) was incorrect. The plugin
requires the tmp_path fixture which was introduced in pytest 3.9.0.

Updated to pytest>=6.2.0 because:
- tmp_path fixture is stable and well-tested
- Contemporary with Python 3.8+ requirement (project requires Python >=3.8)
- Verified all 33 tests pass with pytest 6.2.0 on Python 3.8

Author: omarkohl

pyproject.toml

@@ -32,7 +32,7 @@ classifiers = [
 ]
 requires-python = ">=3.8"
 dependencies = [
-    "pytest>=3.6",
+    "pytest>=6.2.0",
 ]
 
 [dependency-groups]