Remove xlrd as a dependency (#116)

Using xlrd as a dependency only for Python 3.6

Closes #115

Author: DeepSpace2

setup.py

@@ -82,5 +82,11 @@ def find_version(*file_paths):
     # your project is installed. For an analysis of "install_requires" vs pip's
     # requirements files see:
     # https://packaging.python.org/en/latest/requirements.html
-    install_requires=['openpyxl>=2.5,<4', 'colour>=0.1.5,<0.2', 'jsonschema', 'xlrd>=1.0.0,<1.3.0', 'pandas<2']
+    install_requires=[
+        'openpyxl>=2.5,<4',
+        'colour>=0.1.5,<0.2',
+        'jsonschema',
+        'pandas<2',
+        "xlrd>=1.0.0,<1.3.0 ; python_version<='3.6'"
+    ]
 )