Increase test coverage for the `wave` module

[fedonman]

Tests

Several code paths in Lib/wave.py are not exercised by Lib/test/test_wave.py. Most of them are error and validation branches reachable through the public API, so they are easy to cover with small, deterministic tests.

Measuring line coverage of Lib/wave.py while running test_wave (via the stdlib trace module) shows the existing suite covers 317 of 449 executable lines. The uncovered branches include, among others:

Wave_write parameter validation

• setnchannels() rejecting a non-positive channel count
• getnchannels() / getsampwidth() / getframerate() / getparams() when parameters are unset
• setsampwidth() rejecting out-of-range widths
• setcomptype() / setformat() rejecting unsupported values
• the "cannot change parameters after starting to write" guards on every setter
• tell()

Wave_read error handling

• rejecting a WAVE_FORMAT_EXTENSIBLE file whose SubFormat GUID is not PCM
• raising EOFError on a truncated fmt chunk
• skipping unknown chunks between fmt and data
• getfp()
• closing the underlying file when opening a malformed file by path fails

wave.open()

• rejecting an invalid mode

Proposal

Add tests covering these paths. This is test-only (no behavior change), so no Misc/NEWS.d entry is required.

I have a patch ready and will open a PR.

Linked PRs

• gh-153953: Increase test coverage for the wave module #153954