fix(build): Fix express import in gcpfunction

[lobsterkatie]

This fixes a spot where we're importing types only to say that we're importing types only, in order to get rid of a warning in build. (If we don't say so, it gets mad because we only have @types/express, not express, as a listed dependency.)

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	18.75 KB (-6.91% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	58.19 KB (-9.95% 🔽)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	17.49 KB (-7.25% 🔽)
@sentry/browser - ES6 CDN Bundle (minified)	52.43 KB (-9.56% 🔽)
@sentry/browser - Webpack (gzipped + minified)	19.33 KB (-16.84% 🔽)
@sentry/browser - Webpack (minified)	61.44 KB (-24.82% 🔽)
@sentry/react - Webpack (gzipped + minified)	19.35 KB (-16.88% 🔽)
@sentry/nextjs Client - Webpack (gzipped + minified)	42.81 KB (-10.92% 🔽)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	24.41 KB (-6.39% 🔽)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	22.96 KB (-6.24% 🔽)