gh-96954: Fix make regen-unicodedata in out-of-tree builds (#112118)

This avoids:

    python3.13 Tools/unicode/makeunicodedata.py
    python3.13: can't open file '.../build/debug/Tools/unicode/makeunicodedata.py': [Errno 2] No such file or directory
    make: *** [Makefile:1498: regen-unicodedata] Error 2

Re-run `make regen-unicodedata` to update the script path in generated files.

Author: hroncok

Makefile.pre.in

@@ -1348,7 +1348,7 @@ regen-limited-abi: all
 
 .PHONY: regen-unicodedata
 regen-unicodedata:
-	$(PYTHON_FOR_REGEN) Tools/unicode/makeunicodedata.py
+	$(PYTHON_FOR_REGEN) $(srcdir)/Tools/unicode/makeunicodedata.py
 
 
 ############################################################################

Misc/NEWS.d/next/Build/2023-11-15-16-56-20.gh-issue-96954.6FYvKn.rst

@@ -0,0 +1 @@
+Make ``make regen-unicodedata`` work for out-of-tree builds of CPython.