Update required version of go to avoid errors like below

error: unable to parse module file go.mod: go.mod:5: unknown directive: toolchain

go.mod

@@ -1,14 +1,14 @@
 module github.com/ryancurrah/gomodguard
 
-go 1.19
+go 1.21
 
 require (
 	github.com/Masterminds/semver v1.5.0
 	github.com/go-xmlfmt/xmlfmt v1.1.2
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/phayes/checkstyle v0.0.0-20170904204023-bfd46e6a821d
 	github.com/t-yuki/gocover-cobertura v0.0.0-20180217150009-aaee18c8195c
-	golang.org/x/mod v0.11.0
+	golang.org/x/mod v0.16.0
 	gopkg.in/yaml.v2 v2.4.0
 )
 

go.sum

@@ -8,8 +8,8 @@ github.com/phayes/checkstyle v0.0.0-20170904204023-bfd46e6a821d h1:CdDQnGF8Nq9oc
 github.com/phayes/checkstyle v0.0.0-20170904204023-bfd46e6a821d/go.mod h1:3OzsM7FXDQlpCiw2j81fOmAwQLnZnLGXVKUzeKQXIAw=
 github.com/t-yuki/gocover-cobertura v0.0.0-20180217150009-aaee18c8195c h1:+aPplBwWcHBo6q9xrfWdMrT9o4kltkmmvpemgIjep/8=
 github.com/t-yuki/gocover-cobertura v0.0.0-20180217150009-aaee18c8195c/go.mod h1:SbErYREK7xXdsRiigaQiQkI9McGRzYMvlKYaP3Nimdk=
-golang.org/x/mod v0.11.0 h1:bUO06HqtnRcc/7l71XBe4WcqTZ+3AH1J59zWDDwLKgU=
-golang.org/x/mod v0.11.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/mod v0.16.0 h1:QX4fJ0Rr5cPQCF7O9lh9Se4pmwfwskqZfq5moyldzic=
+golang.org/x/mod v0.16.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 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 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=