Deprecate Python 3.6 (#1017)

* Rename CI workflow to a more meaningful name

* News fragment

changelog.d/1017.deprecation.rst

@@ -0,0 +1,2 @@
+Python 3.6 is now deprecated and is slated for removal in the next release.
+If that would affect you, please `let us know <https://github.com/python-attrs/attrs/pull/993>`_.

changelog.d/988.breaking.rst

@@ -1,4 +1 @@
 Python 3.5 is not supported anymore.
-
-We're considering to drop 3.6 soon too.
-If that would affect you, please `let us know <https://github.com/python-attrs/attrs/pull/993>`_.

src/attr/__init__.py

@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: MIT
 
+import sys
+import warnings
+
 from functools import partial
 
 from . import converters, exceptions, filters, setters, validators
@@ -21,6 +24,14 @@ from ._next_gen import define, field, frozen, mutable
 from ._version_info import VersionInfo
 
 
+if sys.version_info < (3, 7):  # pragma: no cover
+    warnings.warn(
+        "Running attrs on Python 3.6 is deprecated & we intend to drop "
+        "support soon. If that's a problem for you, please let us know why & "
+        "we MAY re-evaluate: <https://github.com/python-attrs/attrs/pull/993>",
+        DeprecationWarning,
+    )
+
 __version__ = "22.2.0.dev0"
 __version_info__ = VersionInfo._from_version_string(__version__)