CI: Pin pyodide-build to 0.30.7

Author: mroeschke

.github/workflows/unit-tests.yml

@@ -391,7 +391,7 @@ jobs:
           actions-cache-folder: emsdk-cache
 
       - name: Install pyodide-build
-        run: pip install "pyodide-build>=0.29.2"
+        run: pip install "pyodide-build==0.30.7"
 
       - name: Build pandas for Pyodide
         run: |