Use latest version of bimg (with Avif support)

[sarahcthekey]

Context:
I'm implementing imgix using your Docker image (latest tag 1.2.4), and I noticed when I check the running versions of dependencies I get the following output:

{
  "imaginary": "1.2.4",
  "bimg": "1.1.4",
  "libvips": "8.10.0"
}

Issue
Then i noticed we were getting some unsupported media errors, some for .avif files. Checking the bimg repo I can see .avif support was added in release 1.1.5, I may be being completely daft (sorry), but how can I make sure that the docker image uses the latest version, shall I clone and edit it to install bimg from source into the image?

Thanks in advance.