Fix side effect of setting env variables 'AWS_ACCESS_KEY_ID' and 'AWS_SECRET_ACCESS_KEY'

[thomasmarwitz]

• Added changelog entry

When using the S3FSStore, the environment variables 'AWS_ACCESS_KEY_ID' and 'AWS_SECRET_ACCESS_KEY' are currently set automatically based on the values provided in the url to create the store.

This is a side effect since the credentials are passed explicitly.

Especially in CI, this can be very annoying. Consider this workflow:

1. AWS credentials are assumed via OpenID Connect, the GH action saves the credentials to the default AWS_* env variables
2. A test runs that assumes a role with the given credentials.
3. Inside this test, a minimalkv bucket S3FSStore is created and overwrites the AWS_* env variables
4. Another test now finds the credentials of the assumed role rather than the original ones that were obtained through OpenID Connect

This even occurs in our own CI:

minimalkv/.github/workflows/ci.yml

Lines 82 to 87 in 679b2fb

	- name: Remap AWS Environment Variables
	if: steps.check-id-token.outcome == 'success'
	run: |
	echo "ACCESS_KEY_ID=${{ env.AWS_ACCESS_KEY_ID }}" >> $GITHUB_ENV
	echo "SECRET_ACCESS_KEY=${{ env.AWS_SECRET_ACCESS_KEY }}" >> $GITHUB_ENV
	echo "SESSION_TOKEN=${{ env.AWS_SESSION_TOKEN }}" >> $GITHUB_ENV

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.37%. Comparing base (8106767) to head (2c65224).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #128      +/-   ##
==========================================
- Coverage   85.38%   85.37%   -0.02%     
==========================================
  Files          32       32              
  Lines        2012     2010       -2     
==========================================
- Hits         1718     1716       -2     
  Misses        294      294              

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[thomasmarwitz]

@fhoehle, I was finally able to tackle this Draft PR. Let me know if this LGTY