Set molecule version range to 6.0.0 to 6.0.3

Restrict the required versions of molecule to the versions that are unit
tested with tox.

Set the python version to the minimum required by molecule in that
range.

setup.py

@@ -27,14 +27,17 @@ def find_version():
     },
     install_requires=[
         # molecule plugins are not allowed to mention Ansible as a direct dependency
-        'molecule>=4.0.1',
-        'pyyaml',
+        'molecule>=6.0.0,<=6.0.3',
+        'PyYAML',
         'proxmoxer>=1.3.1',
     ],
     classifiers=[
         'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.10',
+        'Programming Language :: Python :: 3.11',
+        'Programming Language :: Python :: 3.12',
         'License :: OSI Approved :: MIT License',
         'Operating System :: OS Independent',
     ],
-    python_requires='>=3.6',
+    python_requires='>=3.10',
 )