Remove pin on Pylint to support Python 3.11

[GraemeWatt]

• Remove "pylintrc" and "tests/pylintrc" configuration files.
• Tweaked code so that Pylint checks all pass.
• Add Python 3.11 and ROOT 6.30 to matrix in tests.yml.
• Skip Pylint step in CI for Python 3.6 and Python 3.7, since these Python versions are incompatible with Pylint 3.x.
• ROOT binary built with Python 3.12 not yet supported by Micromamba, so don't include Python 3.12 in test matrix.
• Closes #234 and fixes the build currently broken in PR #257.

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📚 Documentation preview 📚: https://hepdata-lib--260.org.readthedocs.build/en/260/

[codecov[bot]]

Codecov Report

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

Project coverage is 89.75%. Comparing base (eb392fe) to head (4baa23f).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #260 +/- ## ========================================== + Coverage 87.99% 89.75% +1.75% ========================================== Files 5 5 Lines 1083 1083 Branches 231 241 +10 ========================================== + Hits 953 972 +19 + Misses 91 80 -11 + Partials 39 31 -8 ``` | [Flag](https://app.codecov.io/gh/HEPData/hepdata_lib/pull/260/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=HEPData) | Coverage Δ | | |---|---|---| | [unittests-3.10](https://app.codecov.io/gh/HEPData/hepdata_lib/pull/260/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=HEPData) | `89.75% <100.00%> (+1.75%)` | :arrow_up: | | [unittests-3.11](https://app.codecov.io/gh/HEPData/hepdata_lib/pull/260/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=HEPData) | `89.75% <100.00%> (?)` | | | [unittests-3.6](https://app.codecov.io/gh/HEPData/hepdata_lib/pull/260/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=HEPData) | `89.45% <100.00%> (+1.77%)` | :arrow_up: | | [unittests-3.7](https://app.codecov.io/gh/HEPData/hepdata_lib/pull/260/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=HEPData) | `89.45% <100.00%> (+1.77%)` | :arrow_up: | | [unittests-3.8](https://app.codecov.io/gh/HEPData/hepdata_lib/pull/260/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=HEPData) | `89.56% <100.00%> (+1.75%)` | :arrow_up: | | [unittests-3.9](https://app.codecov.io/gh/HEPData/hepdata_lib/pull/260/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=HEPData) | `89.56% <100.00%> (+1.75%)` | :arrow_up: | 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=HEPData#carryforward-flags-in-the-pull-request-comment) to find out more.

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