Drop support for Python 3.6.

amaranth/_toolchain/cxx.py

@@ -19,7 +19,7 @@ def build_cxx(*, cxx_sources, output_name, include_dirs, macros):
 
         with warnings.catch_warnings():
             warnings.filterwarnings(action="ignore", category=DeprecationWarning)
-            # This emits a DeprecationWarning on Python 3.6 and 3.10.
+            # This emits a DeprecationWarning on Python 3.10.
             from setuptools import distutils
             cc_driver = distutils.ccompiler.new_compiler()
 

amaranth/_toolchain/yosys.py

@@ -12,14 +12,11 @@ except ImportError:
     except ImportError:
         importlib_metadata = None # not installed
 try:
+    from importlib import resources as importlib_resources
     try:
-        from importlib import resources as importlib_resources
-        try:
-            importlib_resources.files # py3.9+ stdlib
-        except AttributeError:
-            import importlib_resources # py3.8- shim
-    except ImportError:
-        import importlib_resources # py3.6- shim
+        importlib_resources.files # py3.9+ stdlib
+    except AttributeError:
+        import importlib_resources # py3.8- shim
 except ImportError:
     importlib_resources = None