fix(image_search): validate engine parameter and raise ValueError for unsupported values

[HeaTTap]

Fixes #94

Changes

• Updated ImageSearchScraper.scrape and ImageSearchScraper.scrape_async to validate that engine is either "bing" or "google".
• Raises a descriptive ValueError if an unsupported engine string (e.g., "googel") is provided instead of silently defaulting to Bing.
• Added unit tests for both sync and async paths in tests/test_scrapers/test_other.py to verify ValueError is raised as expected.

[Copilot]

Pull request overview

This PR fixes issue #94 by making ImageSearchScraper reject unsupported engine values instead of silently falling back to Bing, and adds regression tests to lock in the behavior.

Changes:

• Validate engine in ImageSearchScraper.scrape and scrape_async and raise ValueError for unsupported values.
• Add sync + async unit tests asserting ValueError is raised for an invalid engine string.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/pyscrappy/scrapers/image_search.py	Adds explicit engine validation and errors for unsupported engines in both sync and async paths.
tests/test_scrapers/test_other.py	Adds sync/async tests verifying unsupported engines raise ValueError.

Suppressed comments (2)

src/pyscrappy/scrapers/image_search.py:82

• ValueError messages in other scrapers start with a capital letter (e.g., src/pyscrappy/scrapers/news.py:78, src/pyscrappy/scrapers/spotify.py:66). For consistency, consider capitalizing this message too.

        if engine not in ("bing", "google"):
            raise ValueError(f"unsupported engine {engine!r}; use 'bing' or 'google'")

tests/test_scrapers/test_other.py:232

• If the ValueError message is capitalized for consistency, this test's regex should be updated to match the new casing.

        with pytest.raises(ValueError, match="unsupported engine 'googel'"):
            await scraper.scrape_async(query="test", engine="googel")

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[vedaant00]

Correct fix and good sync+async coverage, thanks @HeaTTap. Pushed a tiny follow-up: capitalized the ValueError to match the other scrapers (news/imdb/youtube) and dropped a trailing blank line for the format check. Green now.