Drop the Go 1.21.4 requirement in /tools

This is overly restrictive; the build only cares about 1.21 or later.

Signed-off-by: Stephen Kitt <[email protected]>

Author: skitt

tools/go.mod

@@ -1,6 +1,6 @@
 module github.com/submariner-io/submariner-operator/tools
 
-go 1.21.4
+go 1.21
 
 require (
 	github.com/operator-framework/operator-sdk v1.33.0