drop py3.6 interpreter support

Dropped by the fontTools dependency

Author: chrissimpkins

README.md

@@ -26,7 +26,7 @@ font-line is a libre, open source command line tool for OpenType vertical metric
 
 ## Install
 
-font-line is built with Python and is tested with Python 3.6+ interpreters. You can verify your installed Python version on the command line with the command:
+font-line is built with Python and supports Python 3.7+ interpreters. Check your installed Python version on the command line with the command:
 
 ```
 $ python3 --version
@@ -166,7 +166,7 @@ Unix/Linux/OS X users can write this report to a file with the `>` command line
 $ font-line report TheFont.ttf > font-report.txt
 ```
 
-You can modify the `font-report.txt` file path above to the file path string of your choice.
+Modify the `font-report.txt` file path above to the file path string of your choice.
 
 #### Baseline to Baseline Distance Calculations
 

setup.py

@@ -4,6 +4,8 @@
 import sys
 from setuptools import setup, find_packages
 
+REQUIRES_PYTHON = ">=3.7.0"
+
 
 # Use repository Markdown README.md for PyPI long description
 try:
@@ -51,6 +53,7 @@ def version_read():
     author="Christopher Simpkins",
     author_email="[email protected]",
     platforms=["any"],
+    python_requires=REQUIRES_PYTHON,
     packages=find_packages("lib"),
     package_dir={"": "lib"},
     install_requires=["commandlines", "standardstreams", "fontTools"],
@@ -66,10 +69,10 @@ def version_read():
         "Operating System :: OS Independent",
         "Programming Language :: Python",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Topic :: Software Development :: Libraries :: Python Modules",
     ],
 )

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py37
+envlist = py310
 
 [testenv]
 commands =