Fix warnings in Regexp#{match,match?} specs

spec/ruby/core/regexp/match_spec.rb

@@ -89,12 +89,14 @@ describe "Regexp#match" do
 
   ruby_version_is ""..."3.0" do
     it "resets $~ if passed nil" do
-      # set $~
-      /./.match("a")
-      $~.should be_kind_of(MatchData)
+      suppress_warning do
+        # set $~
+        /./.match("a")
+        $~.should be_kind_of(MatchData)
 
-      /1/.match(nil)
-      $~.should be_nil
+        /1/.match(nil)
+        $~.should be_nil
+      end
     end
   end
 
@@ -145,7 +147,9 @@ describe "Regexp#match?" do
 
   ruby_version_is ""..."3.0" do
     it "returns false when given nil" do
-      /./.match?(nil).should be_false
+      suppress_warning do
+        /./.match?(nil).should be_false
+      end
     end
   end