process: fix typo in sc/dmup blurb

Signed-off-by: Mattia Rizzolo <mattia@debian.org>

process/views.py

@@ -412,7 +412,7 @@ class StatementCreate(RequirementMixin, FormView):
             return [
                 "I agree to uphold the Social Contract, the Debian Free Software Guidelines,",
                 "and the Debian Code of Conduct, in my Debian work.",
-                "I have read the Debian Machine Usage Policy and I accept them."
+                "I have read the Debian Machine Usage Policies and I accept them."
             ]
         return None