drop python 3.6, EOL

Author: mr-c

.travis.yml

@@ -3,7 +3,6 @@ branches:
     - main
 language: python
 python:
-- '3.6'
 - '3.7'
 - '3.8'
 - '3.9'

setup.py

@@ -20,7 +20,7 @@
     url="https://github.com/common-workflow-language/cwltool-service",
     download_url="https://github.com/common-workflow-language/cwltool-service",
     license="Apache 2.0",
-    python_requires="~=3.6",
+    python_requires="~=3.7",
     setup_requires=["pytest-runner"],
     tests_require=["pytest"],
     packages=["wes_service", "wes_client"],
@@ -50,7 +50,6 @@
         "Operating System :: MacOS :: MacOS X",
         "Operating System :: POSIX",
         "Programming Language :: Python",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",