tests: use regex for ANSI escape code detection in has_ansi_escape_codes()

[adityamoolya]

Implemented the TODO in tests/test_icecream.py:41 by replacing the oversimplified ANSI escape detection helper with regex-based detection.

Previously has_ansi_escape_codes() only checked for the substring \x1b[, which could produce false positives because it did not validate a complete ANSI CSI escape sequence.

This PR replaces that logic with a precompiled regex that matches full CSI sequences:

_ANSI_CSI_RE = re.compile(r'\x1b[[0-9;]*[A-Za-z]')

Changes included:

• Added import re
• Added compiled _ANSI_CSI_RE
• Updated has_ansi_escape_codes() to use regex matching
• Removed resolved TODO(grun) comment

Testing

All existing tests that depend on has_ansi_escape_codes() (test_coloring, test_non_ascii_characters_no_syntax_highlighting, test_no_color_* suite) continue to pass with no modifications.

[Jakeroid]

@adityamoolya Thank you!

I see there is currently a merge conflict with the main branch. Would you like to resolve it?

[adityamoolya]

@adityamoolya Thank you!

I see there is currently a merge conflict with the main branch. Would you like to resolve it?

Resolved the merge conflict and force-pushed the update. The PR should now merge cleanly.