Please auto-update the Rust version and Docker Hub image

[taeh98]

Hello,

I hope this finds you well.

The issues in this repo show that changes between the different versions of Rust are a frequent source of problems since the Rust version isn't updated often (especially on Docker Hub).

One issue is that the Rust version used in this repo is infrequently updated. Please could you, therefore, take measures to keep it up to date, if possible automatically? Perhaps you could specify the Rust version as "stable" (meaning the most recent stable version), if possible. If not, perhaps a scheduled action could set the Rust version to the most recent stable version at a regular interval. Or perhaps allowing for others to approve pull requests could also help this (and the repo maintenance as a whole). Abstracting the Rust version arguments/constants in the Dockerfile and Makefile to an environment variable or something similar may also help to make the process easier.

Another issue is that even when the Rust version is updated in this repo, the new commit isn't published to Docker Hub. Please could you, therefore, configure this to happen to automatically in GitHub actions? I think this is the purpose of this pull request. This issue is further discussed in this issue as well as this one. This issue is similar but specific to nightly Rust builds. IMHO, stable versions should be the default because of the likely uses of Rust lambda functions - but it doesn't hurt to have both as options.

Thank you for your time and consideration.

[zamazan4ik]

I would like to see such changes in this repo. We've already implemented similar approach here: https://github.com/rust-serverless/lambda-rust

[TristanMenzinger]

Thank you for your work @softprops. Is there anything we can do to help you with this?

I've moved towards building images directly via aws-lambda-rust-runtime, but this package was/is a lot more convenient, especially with Serverless.