v0.2.0

[minor] Drop vendored bindgen patch; quiet Installer on unchanged binary

Bump ext-php-rs to 0.15.14, which uses ext-php-rs-bindgen 0.72.1-extphprs.2
with regular clang-sys — the `links = "clang"` collision against wreq's
boring-sys2 is gone, so the vendored copy under third_party/ and the
`[patch.crates-io]` block are no longer needed. Closes the workaround tracked
in extphprs/ext-php-rs#740.

Installer::run now asks the existing binary for its own version via a clean
PHP subprocess (`-d extension=$path -r '... Wreq\Ext\Client::extensionVersion()'`)
and stays silent when major.minor matches the Composer package. A mismatch
forces a redownload, fixing the stale-binary case after `composer update`
that previously surfaced only at runtime as VersionMismatchException. Dev
checkouts (dev-* package versions) keep their locally-built binary untouched.