Update go.mod to 1.21.6

Choked on left-over submodule vendor folder so deleted that.
https://stackoverflow.com/questions/70808768/what-does-inconsistent-vendoring-mean-in-go

Had to run `go mod tidy` which made all the rest of the changes

go.mod

@@ -1,12 +1,26 @@
 module github.com/timabell/schema-explorer
 
-go 1.13
+go 1.21.6
 
 require (
 	github.com/go-sql-driver/mysql v1.4.1
 	github.com/gorilla/mux v1.7.3
 	github.com/lib/pq v1.2.0
 	github.com/mattn/go-sqlite3 v1.11.0
 	github.com/microsoft/go-mssqldb v1.5.0
+)
+
+require (
+	github.com/golang-sql/civil v0.0.0-20220223132316-b832511892a9 // indirect
+	github.com/golang-sql/sqlexp v0.1.0 // indirect
+	github.com/hashicorp/go-uuid v1.0.3 // indirect
+	github.com/jcmturner/aescts/v2 v2.0.0 // indirect
+	github.com/jcmturner/dnsutils/v2 v2.0.0 // indirect
+	github.com/jcmturner/gofork v1.7.6 // indirect
+	github.com/jcmturner/goidentity/v6 v6.0.1 // indirect
+	github.com/jcmturner/gokrb5/v8 v8.4.4 // indirect
+	github.com/jcmturner/rpc/v2 v2.0.3 // indirect
+	golang.org/x/crypto v0.9.0 // indirect
+	golang.org/x/net v0.10.0 // indirect
 	google.golang.org/appengine v1.6.5 // indirect
 )

go.sum

@@ -109,7 +109,6 @@ golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/appengine v1.6.5 h1:tycE03LOZYQNhDpS27tcQdAzLCVMaj7QT2SXxebnpCM=
 google.golang.org/appengine v1.6.5/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCIDZVag1xfc=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=