Bump github.com/miekg/dns from 1.1.30 to 1.1.31

Bumps [github.com/miekg/dns](https://github.com/miekg/dns) from 1.1.30 to 1.1.31.
- [Release notes](https://github.com/miekg/dns/releases)
- [Changelog](https://github.com/miekg/dns/blob/master/Makefile.release)
- [Commits](https://github.com/miekg/dns/compare/v1.1.30...v1.1.31)

Signed-off-by: dependabot[bot] <support@github.com>

go.mod

@@ -6,7 +6,7 @@ require (
 	github.com/golang/protobuf v1.4.2
 	github.com/google/go-cmp v0.5.1
 	github.com/gorilla/websocket v1.4.2
-	github.com/miekg/dns v1.1.30
+	github.com/miekg/dns v1.1.31
 	github.com/seiflotfy/cuckoofilter v0.0.0-20200511222245-56093a4d3841
 	github.com/stretchr/testify v1.6.1
 	github.com/xiaokangwang/VSign v0.0.0-20200704130305-63f4b4d7a751

go.sum

@@ -50,6 +50,8 @@ github.com/miekg/dns v1.1.29 h1:xHBEhR+t5RzcFJjBLJlax2daXOrTYtr9z4WdKEfWFzg=
 github.com/miekg/dns v1.1.29/go.mod h1:KNUDUusw/aVsxyTYZM1oqvCicbwhgbNgztCETuNZ7xM=
 github.com/miekg/dns v1.1.30 h1:Qww6FseFn8PRfw07jueqIXqodm0JKiiKuK0DeXSqfyo=
 github.com/miekg/dns v1.1.30/go.mod h1:KNUDUusw/aVsxyTYZM1oqvCicbwhgbNgztCETuNZ7xM=
+github.com/miekg/dns v1.1.31 h1:sJFOl9BgwbYAWOGEwr61FU28pqsBNdpRBnhGXtO06Oo=
+github.com/miekg/dns v1.1.31/go.mod h1:KNUDUusw/aVsxyTYZM1oqvCicbwhgbNgztCETuNZ7xM=
 github.com/phayes/freeport v0.0.0-20180830031419-95f893ade6f2 h1:JhzVVoYvbOACxoUmOs6V/G4D5nPVUW73rKvXxP4XUJc=
 github.com/phayes/freeport v0.0.0-20180830031419-95f893ade6f2/go.mod h1:iIss55rKnNBTvrwdmkUpLnDpZoAHvWaiq5+iMmen4AE=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=