Fix lexer selection priority in get_lexer()

[Synvoya]

Summary

get_lexer() returns the wrong lexer for a structured-syntax MIME type with a + suffix when both the subtype name and the suffix resolve to a Pygments lexer — e.g. application/yaml+python highlights as Python instead of YAML.

Root cause

lexer_names is built name-first ([subtype_name, subtype_suffix]), and the sibling MIME-type loop breaks on the first match. But the lexer-name loop has no break:

for name in lexer_names:
    try:
        lexer = pygments.lexers.get_lexer_by_name(name)   # no break -> last wins
    except ClassNotFound:
        pass

so it keeps overwriting lexer and returns the last match (the suffix) instead of the first (the name).

Fix

Add the missing break, mirroring the MIME-type loop, so the first resolving name wins as intended.

Impact

Limited but real: the common structured-suffix types (+json, +xml, +yaml) are unaffected because their name part isn't a Pygments lexer, so first- and last-match coincided. The bug only surfaces when both the name and the suffix are distinct valid lexers.

Tests

Added a parametrized case to TestColors.test_get_lexer asserting application/yaml+python → YAML (fails before the fix, passes after). TestColors: 15 passed; flake8 clean.