chore: update to 1.21 (#366)

go.mod

@@ -1,6 +1,6 @@
 module github.com/googleapis/gax-go
 
-go 1.20
+go 1.21
 
 require (
  github.com/googleapis/gax-go/v2 v2.13.0

go.sum

@@ -1,4 +1,5 @@
 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/googleapis/gax-go/v2 v2.13.0 h1:yitjD5f7jQHhyDsnhKEBU52NdvvdSeGzlAnDPT0hH1s=
 github.com/googleapis/gax-go/v2 v2.13.0/go.mod h1:Z/fvTZXF8/uw7Xu5GuslPw+bplx6SS338j1Is2S+B7A=
 golang.org/x/net v0.27.0 h1:5K3Njcw06/l2y9vpGCSdcxWOYHOUk3dVNGDXN+FvAys=
@@ -11,6 +12,7 @@ google.golang.org/api v0.188.0 h1:51y8fJ/b1AaaBRJr4yWm96fPcuxSo0JcegXE3DaHQHw=
 google.golang.org/api v0.188.0/go.mod h1:VR0d+2SIiWOYG3r/jdm7adPW9hI2aRv9ETOSCQ9Beag=
 google.golang.org/genproto v0.0.0-20240708141625-4ad9e859172b h1:dSTjko30weBaMj3eERKc0ZVXW4GudCswM3m+P++ukU0=
 google.golang.org/genproto/googleapis/api v0.0.0-20240711142825-46eb208f015d h1:kHjw/5UfflP/L5EbledDrcG4C2597RtymmGRZvHiCuY=
+google.golang.org/genproto/googleapis/api v0.0.0-20240711142825-46eb208f015d/go.mod h1:mw8MG/Qz5wfgYr6VqVCiZcHe/GJEfI+oGGDCohaVgB0=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20240711142825-46eb208f015d h1:JU0iKnSg02Gmb5ZdV8nYsKEKsP6o/FGVWTrw4i1DA9A=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20240711142825-46eb208f015d/go.mod h1:Ue6ibwXGpU+dqIcODieyLOcgj7z8+IcskoNIgZxtrFY=
 google.golang.org/grpc v1.64.1 h1:LKtvyfbX3UGVPFcGqJ9ItpVWW6oN/2XqTxfAnwRRXiA=

go.work

@@ -1,4 +1,4 @@
-go 1.20
+go 1.21
 
 use (
  .