Remove puppet 7 support

Puppet 7 already reached its EOL and now we have the newer major
release(8) available.

Change-Id: I8e67e654cbf7e918d6ad40a0d71005376220d969
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

metadata.json

@@ -44,7 +44,7 @@
     "requirements": [
         {
             "name": "puppet",
-            "version_requirement": ">= 7.0.0 < 9.0.0"
+            "version_requirement": ">= 8.0.0 < 9.0.0"
         }
     ],
     "source": "https://opendev.org/openstack/puppet-openstack_extras.git",

releasenotes/notes/remove-puppet-7-2e09b21b71520389.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    Puppet 7 is no longer supported. Use Puppet 8 instead.