gh-36218: src/bin/sage-env: set PYDEVD_DISABLE_FILE_VALIDATION=1

    
This fixes a doctest with newer versions of debugpy, as seen in in
#36141 and
#36129. Explanation in the commit
message.
    
URL: #36218
Reported by: Michael Orlitzky
Reviewer(s): Matthias Köppe

src/bin/sage-env

@@ -635,3 +635,11 @@ if [ -n "$SAGE_LOCAL" ]; then
     fi
 
 fi
+
+
+# Newer versions of debugpy come with a bundled pydevd that complains
+# about >=python-3.11's core modules being frozen (and therefore not
+# breakpoint-able). This workaround simply hides the warning to keep
+# our doctests predictable (which was the status quo with earlier
+# versions of debugpy).
+export PYDEVD_DISABLE_FILE_VALIDATION=1