chore(deps): bump dtolnay/rust-toolchain from 3c5f7ea28cd621ae0bf5283f0e981fb97b8a7af9 to 2c7215f132e9ebf062739d9130488b56d53c060c - #4

…test it (#19)

The README example on this release candidate does not run:

    old = "def greet(name):
        return 'hi ' + name
    "

The triple quotes had collapsed to single quotes, so it dies with
"SyntaxError: unterminated string literal" at PARSE time, before importing
anything. This is the first code a user copies, and it renders on PyPI.

That is 0.0.1 defect #4 again, in a new form. 0.0.1's example raised NameError
because it was a fragment; this one is self-contained but unparseable.

Restored the triple quotes and confirmed it runs, printing exactly what the
README claims two lines below it:

    ChangeType.ADDITION Insert -> if_statement('if_statement')

## The gate could never have caught this

smoke_published_wheel.py already had "a real diff with a known-correct answer",
but it ran OLD_SRC/NEW_SRC — the script's own PRIVATE copy of the example. That
proves the library works. It proves nothing about what we published, which is
precisely the gap that pulled 0.0.1: every check was green.

So the gate now extracts the first ```python fence from the README a user reads
and executes it against the INSTALLED wheel. Verified in both directions:

    repaired README        exit 0  -> gate passes
    the broken RC README   exit 1  -> gate catches it

Found by auditing whether the RC actually contains the fixes 0.0.2 claims to
ship, rather than assuming it did. The other three 0.0.1 defects are genuinely
fixed on this branch.

Co-authored-by: n1ckyb <nicknuxton@icloud.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>