Single place for all the tink stack version

Tinkerbell is made of different components as we all know at this point.

Sandbox had those versions all over the places. This PR moves them as
part of the `envrc` file.

Signed-off-by: Gianluca Arbezzano <gianarb92@gmail.com>

test/_vagrant/vagrant_test.go

@@ -35,7 +35,7 @@ func TestVagrantSetupGuide(t *testing.T) {
 		}
 	}()
 
-	_, err = machine.Exec(ctx, "cd /vagrant/deploy && source ../envrc && docker-compose up -d")
+	_, err = machine.Exec(ctx, "cd /vagrant/deploy && source ../.env && docker-compose up -d")
 	if err != nil {
 		t.Fatal(err)
 	}