PEP 803: fix author formatting

Author: ngoldbaum

peps/pep-0803.rst

@@ -1,7 +1,6 @@
 PEP: 803
 Title: "abi3t": Stable ABI for Free-Threaded Builds
-Author: Petr Viktorin <encukou@gmail.com>
-Author: Nathan Goldbaum <nathan.goldbaum@gmail.com>
+Author: Petr Viktorin <encukou@gmail.com>, Nathan Goldbaum <nathan.goldbaum@gmail.com>
 Discussions-To: https://discuss.python.org/t/106181
 Status: Draft
 Type: Standards Track