refactor: Remove pre-flight checks

[mbeacom]

Summary

This change totally removes the pre-flight checks in favor of guiding the user to evaluate their clusters with something like eksup or other existing cluster upgrade readiness tools.

Additionally, this PR removes pylint in favor of ruff.

Resolves: #113

Changes

Please provide a summary of what's being changed

User experience

No longer providing the --preflight functionality during upgrade or explicitly.

Checklist

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• [x] I have performed a self-review of this change
• [x] Changes have been tested
• [ ] Changes are documented

Acknowledgment

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[codecov-commenter]

Codecov Report

Patch coverage: 22.22% and project coverage change: +10.95 :tada:

Comparison is base (faf227d) 28.75% compared to head (24cb6d2) 39.71%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #112 +/- ## =========================================== + Coverage 28.75% 39.71% +10.95% =========================================== Files 14 13 -1 Lines 1937 1337 -600 =========================================== - Hits 557 531 -26 + Misses 1380 806 -574 ``` | [Impacted Files](https://app.codecov.io/gh/aws-samples/eks-cluster-upgrade/pull/112?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [eksupgrade/src/boto\_aws.py](https://app.codecov.io/gh/aws-samples/eks-cluster-upgrade/pull/112?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-ZWtzdXBncmFkZS9zcmMvYm90b19hd3MucHk=) | `10.84% <0.00%> (ø)` | | | [eksupgrade/cli.py](https://app.codecov.io/gh/aws-samples/eks-cluster-upgrade/pull/112?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-ZWtzdXBncmFkZS9jbGkucHk=) | `23.59% <16.66%> (+0.59%)` | :arrow_up: | | [eksupgrade/\_\_init\_\_.py](https://app.codecov.io/gh/aws-samples/eks-cluster-upgrade/pull/112?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-ZWtzdXBncmFkZS9fX2luaXRfXy5weQ==) | `100.00% <100.00%> (ø)` | | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/aws-samples/eks-cluster-upgrade/pull/112/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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[quixoticmonk]

We should remove the Pre-flights check section in the README or update with the proposal before the version is published.