update pkg_mgr.py for Amazon Linux support (#56618)

(cherry picked from commit 4c00fc7b32)

changelogs/fragments/56618-update-pkg_mgr.py-for-Amazon-Linux-support.yaml

@@ -0,0 +1,2 @@
+bugfixes:
+  - pkg_mgr - Ansible 2.8.0 failing to install yum packages on Amazon Linux (https://github.com/ansible/ansible/issues/56583)

lib/ansible/module_utils/facts/system/pkg_mgr.py

@@ -78,9 +78,11 @@ class PkgMgrFactCollector(BaseFactCollector):
                 # If there's some new magical Fedora version in the future,
                 # just default to dnf
                 pkg_mgr_name = 'dnf'
+        elif collected_facts['ansible_distribution'] == 'Amazon':
+            pkg_mgr_name = 'yum'
         else:
-            # If it's not Fedora and it's Red Hat family of distros, assume RHEL
-            # or a clone. For versions of RHEL < 8 that Ansible supports, the
+            # If it's not one of the above and it's Red Hat family of distros, assume
+            # RHEL or a clone. For versions of RHEL < 8 that Ansible supports, the
             # vendor supported official package manager is 'yum' and in RHEL 8+
             # (as far as we know at the time of this writing) it is 'dnf'.
             # If anyone wants to force a non-official package manager then they