Update to Node 20 in GitHub Actions

[rhigman]

Node 16 is being deprecated in favour of Node 20, which affects some of our GitHub Actions workflows. There are also some which still use Node 12.

Fixed for Docker-based Actions under d2fa6b2, but some remain, e.g. logs at https://github.com/thoth-pub/thoth/actions/runs/8185276928:

Annotations
12 warnings
format_check
Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions-rs/toolchain@v1, actions-rs/cargo@v1. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.
format_check
The following actions uses node12 which is deprecated and will be forced to run on node16: actions-rs/toolchain@v1, actions-rs/cargo@v1. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/
format_check
The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
format_check
The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
format_check
The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
format_check
The `set-output` command is deprecated and will be disabled soon. Please upgrade to using Environment Files. For more information see: https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
build
Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions-rs/cargo@v1. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.
build
The following actions uses node12 which is deprecated and will be forced to run on node16: actions-rs/cargo@v1. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/
lint
Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions-rs/cargo@v1. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.
lint
The following actions uses node12 which is deprecated and will be forced to run on node16: actions-rs/cargo@v1. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/
test
Node.js 16 actions are deprecated. Please update the following actions to use Node.js 20: actions/checkout@v3, actions-rs/cargo@v1. For more information see: https://github.blog/changelog/2023-09-22-github-actions-transitioning-from-node-16-to-node-20/.
test
The following actions uses node12 which is deprecated and will be forced to run on node16: actions-rs/cargo@v1. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/

[ja573]

Fixed under #549