[DPE-5324] Increase ruff rules

[dragomirp]

Add more linting rules and change and suppress the reported issues. Added rules are:

• flake8-bugbear
• ruff specific rules
• flake8-bandit
• flake8-simplify
• pyupdate
• flake8-type-checking

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 90.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 75.05%. Comparing base (b210866) to head (cbff9fb). Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/relations/pgbouncer_provider.py	66.66%	2 Missing and 1 partial :warning:
src/charm.py	93.10%	2 Missing :warning:
src/relations/db.py	0.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #390 +/- ## ========================================== + Coverage 74.50% 75.05% +0.54% ========================================== Files 9 9 Lines 1322 1315 -7 Branches 228 227 -1 ========================================== + Hits 985 987 +2 + Misses 262 255 -7 + Partials 75 73 -2 ```

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