TST: Change quote style in rebase command.

Author: DWesl

.github/workflows/cygwin.yml

@@ -51,7 +51,7 @@ jobs:
           bash -c "/usr/bin/python3.8 -m pip install dist/numpy-*cp38*.whl"
       - name: Rebase NumPy compiled extensions
         run: |
-          bash -c "/usr/bin/rebase --database --oblivious `/bin/dash tools/list_numpy_dlls.sh 3.8`"
+          bash -c "/usr/bin/rebase --database --oblivious $(/bin/dash tools/list_numpy_dlls.sh 3.8)"
       - name: Run NumPy test suite
         run: >-
           dash -c "/usr/bin/python3.8 runtests.py -n -vv"