fix: Conftest can now successfully load files using a file URL (e.g., `file:///C:/path/to/data.yaml`) on windows

[pckvcode]

Conftest encounters errors on Windows when loading file paths that include drive letters (e.g., C:/path/to/data.yaml). Even when using a file URL (e.g., file:///C:/path/to/data.yaml), we still face issues.

With these code changes, Conftest can now successfully load files using a file URL (e.g., file:///C:/path/to/data.yaml).

We opted for file URLs(e.g., file:///C:/path/to/data.yaml) instead of paths with drive letters (e.g., C:/path/to/data.yaml) because OPA does not support file paths with drive letters. For more details, see this issue comment.

Resolves: https://github.com/open-policy-agent/conftest/issues/979

@boranx Can you please review this changes? Thank you

[jalseth]

@pckvcode It looks like the code tests are passing but the style check is not. Please squash your commits and ensure that the commit is prefixed with fix: to follow conventional commits formatting.