Update min go version to 1.21 (#403)

README.md

@@ -29,6 +29,9 @@ label, archive and manage your inbox automatically.
     - [Automatic labels](#automatic-labels)
     - [Multiple Gmail accounts](#multiple-gmail-accounts)
   - [Known issues](#known-issues)
+    - [Apply filters to existing emails](#apply-filters-to-existing-emails)
+    - [OAuth2 authentication errors](#oauth2-authentication-errors)
+    - [YAML config is unsupported](#yaml-config-is-unsupported)
   - [Comparison with existing projects](#comparison-with-existing-projects)
   - [Footnotes](#footnotes)
 
@@ -64,9 +67,9 @@ This project then exists to provide to your Gmail filters:
 
 ## Install
 
-gmailctl is written in Go and requires at least Go version 1.17. Make sure to
-setup your [$GOPATH](https://golang.org/doc/code.html#GOPATH) correctly,
-including the `bin` subdirectory in your `$PATH`.
+gmailctl is written in Go and requires a recent version (see [go.mod](go.mod)).
+Make sure to setup your [`$GOPATH`](https://golang.org/doc/code.html#GOPATH)
+correctly and include its `bin` subdirectory in your `$PATH`.
 
 ```
 go install github.com/mbrt/gmailctl/cmd/gmailctl@latest

go.mod

@@ -1,6 +1,6 @@
 module github.com/mbrt/gmailctl
 
-go 1.17
+go 1.21
 
 require (
 	github.com/google/go-jsonnet v0.20.0
@@ -17,7 +17,6 @@ require (
 require (
 	cloud.google.com/go/auth v0.3.0 // indirect
 	cloud.google.com/go/auth/oauth2adapt v0.2.2 // indirect
-	cloud.google.com/go/compute v1.24.0 // indirect
 	cloud.google.com/go/compute/metadata v0.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
@@ -41,7 +40,6 @@ require (
 	golang.org/x/net v0.24.0 // indirect
 	golang.org/x/sys v0.19.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
-	google.golang.org/appengine v1.6.8 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20240429193739-8cf5692501f6 // indirect
 	google.golang.org/grpc v1.63.2 // indirect
 	google.golang.org/protobuf v1.34.0 // indirect