Ignore DeprecationWarning when decoding string escape sequences - #12

Motivation

• Prevent spurious DeprecationWarning emitted by codecs.decode(..., 'unicode-escape') when decoding ASCII parts of WDL strings so decoding does not pollute logs on newer Python versions.

Description

• Import warnings and wrap the ASCII-part decode in a decode_ascii helper that uses warnings.catch_warnings() with warnings.filterwarnings("ignore", category=DeprecationWarning), and use that helper in String._decode_escapes via String._ASCII_PARTS_RE.sub in WDL/Expr.py.

Testing

• Ran the project's unit tests including string-escape decoding checks and the full test suite with pytest, and the tests completed successfully.

Codex Task