internal/versions: remove use of go/versions

Removes the guarded use of "go/versions" when on GoVersions >=1.22.
Instead always uses the internal fork.

Fixes golang/go#64490
Updates golang/go#32345

Change-Id: I22636c52ddbb89c72edbd0ed65ab6b9a394d70d1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/550395
Reviewed-by: Bryan Mills <bcmills@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Run-TryBot: Tim King <taking@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

Author: timothy-king

internal/versions/versions_go121.go renamed to internal/versions/versions.go

@@ -2,11 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !go1.22
-// +build !go1.22
-
 package versions
 
+// Note: If we use build tags to use go/versions when go >=1.22,
+// we run into go.dev/issue/53737. Under some operations users would see an
+// import of "go/versions" even if they would not compile the file.
+// For example, during `go get -u ./...` (go.dev/issue/64490) we do not try to include
+// For this reason, this library just a clone of go/versions for the moment.
+
 // Lang returns the Go language version for version x.
 // If x is not a valid version, Lang returns the empty string.
 // For example: