🧱 include MQT Core via FetchContent instead of as a submodule

[burgholzer]

Description

https://github.com/cda-tum/mqt-core was included as a submodule so far. This PR removes this submodule and uses the existing fetch content commands to include this dependency.

Furthermore, it adds a dependabot-like update workflow for the FetchContent-managed mqt-core dependency.

Checklist:

• [x] The pull request only contains commits that are related to it.
• [x] I have added appropriate tests and documentation.
• [x] I have made sure that all CI jobs on GitHub pass.
• [x] The pull request introduces no new warnings and follows the project's style guidelines.

[codecov[bot]]

Codecov Report

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

Project coverage is 96.3%. Comparing base (015d0e6) to head (c693bcd).

Additional details and impacted files

[](https://app.codecov.io/gh/cda-tum/mqt-qcec/pull/407?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cda-tum) ```diff @@ Coverage Diff @@ ## main #407 +/- ## ======================================= - Coverage 96.3% 96.3% -0.1% ======================================= Files 35 35 Lines 1818 1817 -1 Branches 224 223 -1 ======================================= - Hits 1751 1750 -1 Misses 67 67 ``` | [Flag](https://app.codecov.io/gh/cda-tum/mqt-qcec/pull/407/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cda-tum) | Coverage Δ | | *Carryforward flag | |---|---|---|---| | [cpp](https://app.codecov.io/gh/cda-tum/mqt-qcec/pull/407/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cda-tum) | `96.0% <ø> (-0.1%)` | :arrow_down: | | | [python](https://app.codecov.io/gh/cda-tum/mqt-qcec/pull/407/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cda-tum) | `97.2% <ø> (ø)` | | Carriedforward from [015d0e6](https://app.codecov.io/gh/cda-tum/mqt-qcec/commit/015d0e6008c52dbb63556367010d1b27250f3cec?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cda-tum) | *This pull request uses carry forward flags. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cda-tum) to find out more. [see 1 file with indirect coverage changes](https://app.codecov.io/gh/cda-tum/mqt-qcec/pull/407/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=cda-tum)

[burgholzer]

The failure here will be resolved by #405