ci: correct capitalization of MarkTechson in pullapprove

Correct the capitalization of MarkTechson's username to match their GitHub profile, ensuring proper evaluation by PullApprove.

Author: josephperrott

.pullapprove.yml

@@ -434,7 +434,7 @@ groups:
         ])
     reviewers:
       users:
-        - marktechson
+        - MarkTechson
         - kirjs
         - ~JeanMeche
         - ~dgp1130