Picks test branch based on current branch

#@nowheel @NoBasis

.github/workflows/build-test-wheel.yml

@@ -52,6 +52,16 @@ jobs:
     steps:
     - uses: actions/checkout@v4
 
+    -name: Check branch and define test branch
+      env:
+        BRANCH_NAME: ${{ github.head_ref || github.ref_name }} 
+     run: |
+        if [[ ${BRANCH_NAME} == *"master"* ]]; then
+            echo "testbranch=pytests" >> $GITHUB_ENV
+        else
+            echo "testbranch=pytests-develop" >> $GITHUB_ENV
+        fi
+
     - name: Set up Python ${{ matrix.python-version }}
       uses: actions/setup-python@v5
       with:
@@ -68,10 +78,10 @@ jobs:
       run: |
         python -m pip install . -C "--build-option=--serial"
 
-    - name: Return to pytests branch
+    - name: Switch to pytests branch
       uses: actions/checkout@v4
       with:
-        ref: pytests-develop
+        ref: env.testbranch
         repository: LLNL/UEDGE 
 
     - name: Test with pytest