Update flannel to fix NAT issue with old iptables version

Signed-off-by: Roberto Bonafiglia <roberto.bonafiglia@suse.com>

go.mod

@@ -97,7 +97,7 @@ require (
 	github.com/coreos/go-systemd v0.0.0-20191104093116-d3cd4ed1dbcf
 	github.com/docker/docker v20.10.23+incompatible
 	github.com/erikdubbelboer/gspt v0.0.0-20190125194910-e68493906b83
-	github.com/flannel-io/flannel v0.21.3
+	github.com/flannel-io/flannel v0.21.4
 	github.com/go-bindata/go-bindata v3.1.2+incompatible
 	github.com/go-sql-driver/mysql v1.6.0
 	github.com/go-test/deep v1.0.7

go.sum

@@ -301,8 +301,8 @@ github.com/fatih/camelcase v1.0.0/go.mod h1:yN2Sb0lFhZJUdVvtELVWefmrXpuZESvPmqwo
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
 github.com/felixge/httpsnoop v1.0.3 h1:s/nj+GCswXYzN5v2DpNMuMQYe+0DDwt5WVCU6CWBdXk=
 github.com/felixge/httpsnoop v1.0.3/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
-github.com/flannel-io/flannel v0.21.3 h1:MlFNP7Jav/dsTPYLEaorZrZpBiW/SRMFk2lHip/LJeU=
-github.com/flannel-io/flannel v0.21.3/go.mod h1:G2mprs/a241vGL0Ha9DDY/Fthx2xDt0WQkJEyspBfMk=
+github.com/flannel-io/flannel v0.21.4 h1:Dsm7eNcTPYg9XS/zsXogLfMfyeJba0X5O2EIcNnaYII=
+github.com/flannel-io/flannel v0.21.4/go.mod h1:G2mprs/a241vGL0Ha9DDY/Fthx2xDt0WQkJEyspBfMk=
 github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568/go.mod h1:xEzjJPgXI435gkrCt3MPfRiAkVrwSbHsst4LCFVfpJc=
 github.com/form3tech-oss/jwt-go v3.2.3+incompatible h1:7ZaBxOI7TMoYBfyA3cQHErNNyAWIKUMIwqxEtgHOs5c=
 github.com/form3tech-oss/jwt-go v3.2.3+incompatible/go.mod h1:pbq4aXjuKjdthFRnoDwaVPLA+WlJuPGy+QneDUgJi2k=