CI: Disable caching (apache#2268)

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# Rationale for this change

Looks like something changed, which caused the CI to fail:
https://github.com/apache/iceberg-python/commits/main/

First attempt to isolate the issue (checking if it is related to
coverage)

# Are these changes tested?

# Are there any user-facing changes?

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Author: Fokko

.github/workflows/python-ci.yml

@@ -56,8 +56,6 @@ jobs:
     - uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python }}
-        cache: poetry
-        cache-dependency-path: ./poetry.lock
     - name: Install system dependencies
       run: sudo apt-get update && sudo apt-get install -y libkrb5-dev # for kerberos
     - name: Install