testing: Pin pyln-testing and pyln-client to 24.02

24.08 broke the plugin handling in CLN by no longer passing the description
along. We'll need to unpin them again once we have switched to CLN 24.08
for testing.

Author: cdecker

libs/gl-testing/pyproject.toml

@@ -12,7 +12,8 @@ dependencies = [
     "grpcio>=1.66.0",
     "httpx>=0.27.2",
     "purerpc>=0.8.0",
-    "pyln-testing==24.8.1",
+    "pyln-client==24.2",
+    "pyln-testing==24.2",
     "pytest-timeout>=2.3.1",
     "pytest-xdist>=3.6.1",
     "rich>=13.9.3",