RHEL8: switch to gem::version check, not float

The code works for 8.9, but once you reach 8.10, the `.to_f()` calls
turns 8.10 into a float, which compared to 8.4 is indeed "less than".

Author: nyetsche

cookbooks/aws-parallelcluster-environment/resources/efa/efa_redhat8.rb

@@ -22,7 +22,11 @@
 
 action_class do
   def efa_supported?
-    if node['platform_version'].to_f < 8.4
+    require 'rubygems'
+    minver = Gem::Version.new("8.4")
+    ourver = Gem::Version.new(node['platform_version'])
+
+    if ourver < minver
       log "EFA is not supported in this RHEL version #{node['platform_version']}, supported versions are >= 8.4" do
         level :warn
       end