Add rod-chapman to pqcp-contributors

rod-chapman has been making various contributions to mlkem-c-aarch64 and it would be great if he could also review other pull requests. My understanding is that adding him to the pqcp-contributors would allow that. 

Signed-off-by: Matthias J. Kannwischer <[email protected]>

config.yaml

@@ -80,6 +80,7 @@ teams:
       - tfaoliveira
       - ashman-p
       - ydoroz
+      - rod-chapman
   - name: pqcp-embedded-admin
     maintainers:
       - mkannwischer