Bump antlr driver to try avoiding memory leak

Author: clems4ever

go.mod

@@ -5,7 +5,7 @@ go 1.13
 require (
 	github.com/VividCortex/mysqlerr v0.0.0-20201215173831-4c396ae82aac
 	github.com/abbot/go-http-auth v0.4.0
-	github.com/antlr/antlr4 v0.0.0-20200103163232-691acdc23f1f
+	github.com/antlr/antlr4 v0.0.0-20210221031308-60fd27ff93a8
 	github.com/deckarep/golang-set v1.7.1
 	github.com/go-sql-driver/mysql v1.5.0
 	github.com/golang-collections/go-datastructures v0.0.0-20150211160725-59788d5eb259

go.sum

@@ -17,8 +17,8 @@ github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuy
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
-github.com/antlr/antlr4 v0.0.0-20200103163232-691acdc23f1f h1:wUtLHuPO/sScvJYvntGmS2jSll+CtxTDpzZNvCXJepw=
-github.com/antlr/antlr4 v0.0.0-20200103163232-691acdc23f1f/go.mod h1:T7PbCXFs94rrTttyxjbyT5+/1V8T2TYDejxUfHJjw1Y=
+github.com/antlr/antlr4 v0.0.0-20210221031308-60fd27ff93a8 h1:U9u8WXsKqHa6T2QJpatkePkDKqesefzIQCMXGWIDTD8=
+github.com/antlr/antlr4 v0.0.0-20210221031308-60fd27ff93a8/go.mod h1:T7PbCXFs94rrTttyxjbyT5+/1V8T2TYDejxUfHJjw1Y=
 github.com/apache/thrift v0.12.0/go.mod h1:cp2SuWMxlEZw2r+iP2GNCdIi4C1qmUzdZFSVb+bacwQ=
 github.com/apache/thrift v0.13.0/go.mod h1:cp2SuWMxlEZw2r+iP2GNCdIi4C1qmUzdZFSVb+bacwQ=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=