Bump Python required version to 3.7

3.6 is no longer supported and we want to switch to asyncio.run which
has been added in Python 3.7

Signed-off-by: Julian Oes <[email protected]>

README.md

@@ -9,7 +9,7 @@ The Python wrapper is based on a gRPC client communicating with the gRPC server
 
 ## Important Notes
 
-- Python 3.6+ is required (because the wrapper is based on [asyncio](https://docs.python.org/3.7/library/asyncio.html)).
+- Python 3.7+ is required (because the wrapper is based on [asyncio](https://docs.python.org/3.7/library/asyncio.html)).
 - You may need to run `pip3` instead of `pip` and `python3` instead of `python`, depending of your system defaults.
 - Auterion has a [Getting started with MAVSDK-Python](https://auterion.com/getting-started-with-mavsdk-python/) guide if you're a beginner and not sure where to start.
 

mavsdk/source/index.rst

@@ -23,7 +23,7 @@ MAVSDK-Python API reference
 Important Notes
 ---------------
 
-- Python 3.6+ is required.
+- Python 3.7+ is required.
 - You may need to run ``pip3`` instead of ``pip`` and ``python3`` instead of ``python``, depending of your system defaults.
 - Auterion has a _Getting started with MAVSDK-Python: https://auterion.com/getting-started-with-mavsdk-python/ guide if you're a beginner and not sure where to start.
 

setup.py

@@ -136,15 +136,15 @@ def version():
     url="https://github.com/mavlink/MAVSDK-Python",
     maintainer="Jonas Vautherin, Julian Oes",
     maintainer_email="[email protected], [email protected]",
-    python_requires='>=3.6',
+    python_requires='>=3.7',
     include_package_data=True,
     cmdclass={'build': custom_build},
 
     classifiers=[
         "Development Status :: 5 - Production/Stable",
         "Intended Audience :: Developers",
         "License :: OSI Approved :: BSD License",
-        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
     ],
 
     packages=find_packages(exclude=["other", "docs", "tests", "examples",