Remove now-unneeded cppcheck suppression

Author: martinhsv

test/cppcheck_suppressions.txt

@@ -47,7 +47,6 @@ constStatement:test/common/modsecurity_test.cc:82
 danglingTemporaryLifetime:src/modsecurity.cc:206
 functionStatic:src/operators/geo_lookup.h:35
 duplicateBreak:src/operators/validate_utf8_encoding.cc
-duplicateBranch:src/request_body_processor/multipart.cc:91
 syntaxError:src/transaction.cc:62
 noConstructor:src/variables/variable.h:152
 duplicateBranch:src/request_body_processor/multipart.cc:93