re-cythonize with a constrained cython version

Constrained the Cython version to be less than 3.0, but greater than
0.29.34.
Updated the setup.py to account for the updated cythonize parameters.
Also made the appveyor version PEP440 compatible

ci/appveyor/fix_version.py

@@ -5,7 +5,8 @@
 import sys
 
 def get_describe_tag():
-    return subprocess.check_output(['git', 'describe', '--tags']).strip().decode('utf-8')
+    ver, change, commit = subprocess.check_output(['git', 'describe', '--tags']).strip().decode('utf-8')
+    return f"{ver}+{change}.{commit}"  # PEP440 compatible
 
 def make_version_file(basedir):
     rev = os.environ.get('APPVEYOR_REPO_COMMIT',

requirements_dev.txt

@@ -1,4 +1,4 @@
-cython
+cython>=0.29.34,<3.0.0
 flake8
 jinja2
 sphinx

setup.py

@@ -45,15 +45,15 @@
 _fwd_default = 0
 _comp_args = ["-O2"] if not ON_WINDOWS else None
 
-cython_directives = {'embedsignature': True,
+compiler_directives = {'embedsignature': True,
                      'boundscheck': False,
                      'optimize.use_switch': True,
                      'wraparound': False,
                      'language_level': 2,
 }
 cython_args = {
-    'cython_directives': cython_directives,
-    'cython_compile_time_env': {},
+    'compiler_directives': compiler_directives,
+    'compile_time_env': {},
 }
 
 if USING_CYTHON: