CI: add warning when not in pandas dev and running stubtest (#48267)

* add warning when not in pandas dev and running stubtest

* add url to the warning

* add trailing underscore in version

* Format the warning message

* resolve review comments

Co-authored-by: Ambuj Pawar <ambuj.pawar95@gmail.com>

scripts/run_stubtest.py

@@ -8,15 +8,26 @@
 
 import pandas as pd
 
+pd_version = getattr(pd, "__version__", "")
+
 # fail early if pandas is not installed
-if not getattr(pd, "__version__", ""):
+if not pd_version:
     # fail on the CI, soft fail during local development
     warnings.warn("You need to install the development version of pandas")
     if pd.compat.is_ci_environment():
         sys.exit(1)
     else:
         sys.exit(0)
 
+# GH 48260
+if "dev" not in pd_version:
+    warnings.warn(
+        f"stubtest may fail as {pd_version} is not a dev version. "
+        f"Please install a pandas dev version or see https://pandas.pydata.org/"
+        f"pandas-docs/stable/development/contributing_codebase.html"
+        f"#validating-type-hints on how to skip the stubtest"
+    )
+
 
 _ALLOWLIST = [  # should be empty
     # TODO (child classes implement these methods)