Remove version restricions on xarray in CI config

xarray has made a bugfix release, so we can just use the latest version
again.

Author: johnomotani

.github/workflows/pythonpackage.yml

@@ -62,7 +62,7 @@ jobs:
         pip install .[tests]
     - name: Integrated tests
       run: |
-        pip install pytest "xarray!=2025.6.0"
+        pip install pytest xarray
         cd integrated_tests/
         ./test_suite.py
 
@@ -123,7 +123,6 @@ jobs:
     - name: Install dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install pytest "xarray!=2025.6.0" # Install explicitly so we can avoid this buggy version
         pip install xbout
         pip install -e .
     - name: Utilities