Pin radical-pilot to version 1.47

A recently released version, 1.48, doesn't work with this executor, so this PR
aggressively constrains the version to what was passing in Parsl GitHub Actions
over the last few weeks.

For further contex, see
radical-cybertools/radical.saga#885 (comment)

setup.py

@@ -34,7 +34,7 @@
     'workqueue': ['work_queue'],
     'flux': ['pyyaml', 'cffi', 'jsonschema'],
     'proxystore': ['proxystore'],
-    'radical-pilot': ['radical.pilot'],
+    'radical-pilot': ['radical.pilot==1.47'],
     # Disabling psi-j since github direct links are not allowed by pypi
     # 'psij': ['psi-j-parsl@git+https://github.com/ExaWorks/psi-j-parsl']
 }