downloads: upgrade setuptools to 49.6.0

As part of this we needed to update a patch so it applies against
the new version of the vendored packaging package.

Author: indygreg

cpython-unix/build-cpython.sh

@@ -327,12 +327,12 @@ index ec9942f0..1b306ca7 100644
 --- a/setuptools/_vendor/packaging/tags.py
 +++ b/setuptools/_vendor/packaging/tags.py
 @@ -283,7 +283,10 @@ def _glibc_version_string():
-     # manpage says, "If filename is NULL, then the returned handle is for the
-     # main program". This way we can let the linker do the work to figure out
      # which libc our process is actually using.
--    process_namespace = ctypes.CDLL(None)
+     #
+     # Note: typeshed is wrong here so we are ignoring this line.
+-    process_namespace = ctypes.CDLL(None)  # type: ignore
 +    try:
-+        process_namespace = ctypes.CDLL(None)
++        process_namespace = ctypes.CDLL(None)  # type: ignore
 +    except OSError:
 +        return None
      try:

pythonbuild/downloads.py

@@ -276,10 +276,10 @@
         "version": "1.30.1",
     },
     "setuptools": {
-        "url": "https://files.pythonhosted.org/packages/b5/96/af1686ea8c1e503f4a81223d4a3410e7587fd52df03083de24161d0df7d4/setuptools-46.1.3.zip",
-        "size": 862431,
-        "sha256": "795e0475ba6cd7fa082b1ee6e90d552209995627a2a227a47c6ea93282f4bfb1",
-        "version": "46.1.3",
+        "url": "https://files.pythonhosted.org/packages/38/cc/db23dbe4efc464c3c0111fedf7d46de8888f05b09488d610f6f8ab6e2544/setuptools-49.6.0.zip",
+        "size": 2188590,
+        "sha256": "46bd862894ed22c2edff033c758c2dc026324788d758e96788e8f7c11f4e9707",
+        "version": "49.6.0",
     },
     "sqlite": {
         "url": "https://www.sqlite.org/2020/sqlite-autoconf-3330000.tar.gz",