Refactor ci with nix

[yanganto]

• CI will use MSRV from Rust manifest (Cargo.toml)
• Reduce usage of actions-rs, which are no longer maintained after Oct 13, 2023.
• Set up dependency upgrade bot
• Refactor lint, test, build with Nix
• Allow codecov upload failure

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 0.0%. Comparing base (c7b261d) to head (1cc6f51). Report is 10 commits behind head on master.

:exclamation: Current head 1cc6f51 differs from pull request most recent head c12841b

Please upload reports for the commit c12841b to get more accurate results.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #25 +/- ## ====================================== Coverage 0.0% 0.0% ====================================== Files 17 17 Lines 3151 3031 -120 ====================================== + Misses 3151 3031 -120 ``` | [Flag](https://app.codecov.io/gh/BP-WG/bp-std/pull/25/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BP-WG) | Coverage Δ | | |---|---|---| | [rust](https://app.codecov.io/gh/BP-WG/bp-std/pull/25/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BP-WG) | `0.0% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=BP-WG#carryforward-flags-in-the-pull-request-comment) to find out more.

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[dr-orlovsky]

can you please also remove dependabot from here?