Update pinned packages in test_requirements.txt

The latest packages don't all work in Python 3.5/3.6, so the latest versions
that work with Python 3.6 are pinned (by creating a virtualenv with Python
3.6 and then using pip freeze), Python 3.5 is dropped from Travis, and the
README is updated to indicate testing starts with version 3.6.

Author: JoshData

.travis.yml

@@ -5,10 +5,8 @@ cache: pip
 
 python:
 #- '2.7'
-#- '3.4'
-- '3.5'
 - '3.6'
-#- '3.7'
+- '3.7'
 - '3.8'
 - '3.9'
 

README.md

@@ -2,7 +2,7 @@ email-validator: Validate Email Addresses
 =========================================
 
 A robust email address syntax and deliverability validation library for
-Python 3.5+ by [Joshua Tauberer](https://joshdata.me).
+Python by [Joshua Tauberer](https://joshdata.me).
 
 This library validates that a string is of the form `[email protected]`. This is
 the sort of validation you would want for an email-based login form on 
@@ -32,6 +32,10 @@ This library was first published in 2015. The current version is 1.1.1
 from `validate_email` has changed, but dict-style access to the validated
 address information still works, so it is backwards compatible.**
 
+This library is tested with Python 3.6+ but should work in earlier versions:
+
+[![Build Status](https://app.travis-ci.com/JoshData/python-email-validator.svg?branch=main)](https://app.travis-ci.com/JoshData/python-email-validator)
+
 Installation
 ------------
 

setup.cfg

@@ -16,8 +16,6 @@ classifiers =
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.5
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9

test_requirements.txt

@@ -1,6 +1,26 @@
-coverage==4.5.4
-docutils==0.15.2
-flake8==3.7.9
-pytest==5.2.2
-pytest-cov==2.8.1
-idna>=2.8
+# This file was generated by running
+#   pip install dnspython idna # from setup.cfg
+#   pip install pytest pytest-cov coverage flake8
+#   pip freeze
+# in a virtualenv with Python 3.6. (Some packages' latest versions
+# are not compatible with Python 3.6, so we must pin versions for
+# repeatable testing in earlier versions of Python.)
+attrs==21.4.0
+coverage==6.2
+dnspython==2.2.1
+flake8==4.0.1
+idna==3.3
+importlib-metadata==4.2.0
+iniconfig==1.1.1
+mccabe==0.6.1
+packaging==21.3
+pluggy==1.0.0
+py==1.11.0
+pycodestyle==2.8.0
+pyflakes==2.4.0
+pyparsing==3.0.7
+pytest==7.0.1
+pytest-cov==3.0.0
+tomli==1.2.3
+typing_extensions==4.1.1
+zipp==3.6.0