Fail with gulp@5

After upgrading gulp to version 5, everything in the project works except this plugin. For some reason, `image-size` stops recognizing the file type.

```
TypeError: unsupported file type: undefined (file: undefined)
at lookup (/home/firefoxic/Projects/test/node_modules/image-size/dist/index.js:43:11)
at Object.imageSize [as default] (/home/firefoxic/Projects/test/node_modules/image-size/dist/index.js:99:16)
at _loop_1 (/home/firefoxic/Projects/test/node_modules/gulp-sharp-responsive/lib/index.js:98:61)
at Transform._transform (/home/firefoxic/Projects/test/node_modules/gulp-sharp-responsive/lib/index.js:143:13)
at Transform._read (/home/firefoxic/Projects/test/node_modules/through2/node_modules/readable-stream/lib/_stream_transform.js:166:10)
at Transform._write (/home/firefoxic/Projects/test/node_modules/through2/node_modules/readable-stream/lib/_stream_transform.js:155:83)
at doWrite (/home/firefoxic/Projects/test/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:390:139)
at writeOrBuffer (/home/firefoxic/Projects/test/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:381:5)
at Writable.write (/home/firefoxic/Projects/test/node_modules/through2/node_modules/readable-stream/lib/_stream_writable.js:302:11)
at ReadableState.drain (/home/firefoxic/Projects/test/node_modules/streamx/index.js:343:47)
```

Reproduce the failure with gulp@5 and inspect the values passed from gulp-sharp-responsive/lib/index.js:_loop_1 and Transform._transform into image-size. Confirm that supported image files are recognized again under gulp@5, using any existing project test or fixture if available.

Written by the indexing model from the issue text.