Bump bs4 and remove lxml upper limit

[Dev-iL]

Description

• Bump the minimum version of bs4 to the latest available.
• Remove the upper limit from the lxml dependency.
• Add a .gitignore with some common ignore paths.

Motivation and Context

lxml is a transitive dependency of amazon-redshift-python-driver. lxml<6 seemingly supports Python 3.14, but publishes no wheels for this version. As a result, installing amazon-redshift-python-driver on Python 3.14 requires compilation - making installation take longer and require additional tools that might not be present on e.g. a CI worker.

Fixes: #263

Testing

Ran the 28 local unit tests after updating both versions.

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• Local run of ./build.sh succeeds
• Code changes have been run against the repository's pre-commit hooks
• Commit messages follow Conventional Commit Specification
• I have read the README document
• I have added tests to cover my changes
• I have run all unit tests using pytest test/unit and they are passing.

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