pygettext: false positives when extracting messages

[tomasr8]

Bug report

Bug description:

Originally came up here: #126755 (comment)

To summarize, pygettext produces a warning for this code:

def _(x):
    pass

The reason is that it confuses the function definition with a function call. I have a PR ready.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-126807: pygettext: Do not attempt to extract messages from function definitions. #126808
• [3.13] gh-126807: pygettext: Do not attempt to extract messages from function definitions. (GH-126808) #126846
• [3.12] gh-126807: pygettext: Do not attempt to extract messages from function definitions. (GH-126808) #126847