Drop support for Python 2

.github/workflows/examples.yml

@@ -8,7 +8,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-16.04, windows-latest, macos-latest]
-        python-version: [2.7, 3.7]
+        python-version: [3.7]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v2

platformio/maintenance.py

@@ -40,6 +40,8 @@ from platformio.proc import is_container
 
 
 def on_platformio_start(ctx, force, caller):
+    ensure_python3(raise_exception=True)
+
     app.set_session_var("command_ctx", ctx)
     app.set_session_var("force_option", force)
     set_caller(caller)
@@ -47,24 +49,8 @@ def on_platformio_start(ctx, force, caller):
 
     if PlatformioCLI.in_silence():
         return
-
     after_upgrade(ctx)
 
-    if not ensure_python3(raise_exception=False):
-        click.secho(
-            """
-Python 2 and Python 3.5 are not compatible with PlatformIO Core 5.0.
-Please check a migration guide on how to fix this warning message:
-""",
-            fg="yellow",
-        )
-        click.secho(
-            "https://docs.platformio.org/en/latest/core/migration.html"
-            "#drop-support-for-python-2-and-3-5",
-            fg="blue",
-        )
-        click.echo("")
-
 
 def on_platformio_end(ctx, result):  # pylint: disable=unused-argument
     if PlatformioCLI.in_silence():

setup.py

@@ -58,9 +58,6 @@ setup(
     author_email=__email__,
     url=__url__,
     license=__license__,
-    python_requires=", ".join(
-        [">=2.7", "!=3.0.*", "!=3.1.*", "!=3.2.*", "!=3.3.*", "!=3.4.*"]
-    ),
     install_requires=minimal_requirements + ([] if PY2 else home_requirements),
     packages=find_packages(exclude=["tests.*", "tests"]) + ["scripts"],
     package_data={
@@ -87,7 +84,6 @@ setup(
         "Operating System :: OS Independent",
         "Programming Language :: C",
         "Programming Language :: Python",
-        "Programming Language :: Python :: 2",
         "Programming Language :: Python :: 3",
         "Topic :: Software Development",
         "Topic :: Software Development :: Build Tools",

tox.ini

@@ -13,13 +13,13 @@
 # limitations under the License.
 
 [tox]
-envlist = py27,py37,py38,py39
+envlist = py36,py37,py38,py39
 
 [testenv]
 passenv = *
 usedevelop = True
 deps =
-    py36,py37,py38,py39: black
+    black
     isort
     pylint
     pytest