Update aws-go dependencies

It looks like the PRs that automatically update Go dependencies haven't been merged in a while.

To make it easier to get started trying the Go generics preview, update the dependencies for the aws-go template to the latest versions, along with the Go 1.20 (Go 1.18 and 1.19 are no longer supported). That way, users trying out generics, only have to update the `pulumi-aws` dependency to the preview branch, and don't have to update the core Pulumi SDK to a more recent version.

aws-go/go.mod

@@ -1,8 +1,8 @@
 module ${PROJECT}
 
-go 1.18
+go 1.20
 
 require (
-	github.com/pulumi/pulumi-aws/sdk/v6 v6.0.2
-	github.com/pulumi/pulumi/sdk/v3 v3.78.1
+	github.com/pulumi/pulumi-aws/sdk/v6 v6.2.0
+	github.com/pulumi/pulumi/sdk/v3 v3.84.0
 )