test: Set .pl and .t as program-extensions for perlcritic

This should help perlcritic discern when not to apply module checks on
programs.

test/100_critic/perlcriticrc

@@ -1,6 +1,7 @@
 # Perl Critic configuration file
 severity = 1
 verbose = %f %l:%c (Severity: %s)\n  %P (%s)\n  near '%r'\n%d\n
+program-extensions = .pl .t
 
 [RegularExpressions::ProhibitUnusualDelimiters]
 allow_all_brackets = 1