Allow github token to be retrieved from a deferred function

This allows you to

```
class{'github_actions_runner':
  personal_access_token => Deferred('secret::get',['poc']),
}
```

for the existing case where a string is used the module will operate in
the same way.

manifests/instance.pp

@@ -131,7 +131,7 @@
     mode    => '0755',
     owner   => $user,
     group   => $group,
-    content => epp('github_actions_runner/configure_install_runner.sh.epp', {
+    content => deferrable_epp('github_actions_runner/configure_install_runner.sh.epp', {
       personal_access_token => $personal_access_token,
       token_url             => $token_url,
       instance_name         => $instance_name,

metadata.json

@@ -10,7 +10,7 @@
   "dependencies": [
     {
       "name": "puppetlabs-stdlib",
-      "version_requirement": ">= 1.0.0 < 7.0.0"
+      "version_requirement": ">= 8.4.0 < 10.0.0"
     },
     {
       "name": "camptocamp/systemd",