Fix block quote in run statement.

It looks like this was omitted by accident, and somehow it worked anyway
until recently.

.github/workflows/dev.yaml

@@ -28,7 +28,6 @@ jobs:
           python-version: ${{ matrix.python-version }}
 
       - name: install developer dependencies
-      # missing pipe on next line
-        run:
+        run: |
           pip install --upgrade pip
           pip install -r requirements.txt