Fix dependencies in earlier versions of Python

which is Python 2.7 and Python 3.5.

We highly recommend you not to use them.

README-cn.rst

@@ -30,6 +30,8 @@
 
 * Python 2.7 或 Python 3
 
+推荐使用 Python 3.6 或更高版本的 Python。
+
 
 快速开始
 -------------

README.rst

@@ -33,7 +33,7 @@ Requirements
 -------------
 * Python 2.7 or Python 3
 
-That's all. It's a simple but smart program.
+We recommend you to use Python 3.6 or higher version of Python.
 
 
 Quick Start

autoremovetorrents/compatibility/pyyaml_version_.py

@@ -0,0 +1,7 @@
+import sys
+
+# The pyyaml offical dropped support for Python < 3.6 in its latest version.
+# To make our program still available in earlier versions of Python,
+# we select an older version of pyyaml manually. (Not Recommend)
+
+PYYAML_VERSION = 'pyyaml' if sys.version_info >= (3, 6, 0) else 'pyyaml==5.4.1'

setup.py

@@ -4,6 +4,7 @@
 from autoremovetorrents.version import __version__
 from autoremovetorrents.compatibility.disk_usage_ import SUPPORT_SHUTIL
 from autoremovetorrents.compatibility.open_ import open_
+from autoremovetorrents.compatibility.pyyaml_version_ import PYYAML_VERSION
 
 setup(name = 'autoremove-torrents',
     version = __version__,
@@ -28,7 +29,7 @@
         'enum34',
         'ply',
         '' if SUPPORT_SHUTIL else 'psutil',
-        'pyyaml',
+        PYYAML_VERSION,
         'requests',
     ],
     entry_points = {