dvc: drop 3.6 support (#6792)

* dvc: drop 3.6 support

Considering that 3.6 has ~2 months until EOL, and our deps are
dropping support for it already (e.g. pygit2), we are droppipping
it as well. This will reduce the load on our test CI as well, since
we've started supporting 3.10 recently.

* setup.cfg: adjust requirements

* daemon: remove 3.6 logic

* tests: utils: remove pre 3.7 logic

tests/utils/httpd.py

@@ -1,6 +1,5 @@
 import hashlib
 import os
-import sys
 import threading
 from contextlib import contextmanager
 from http import HTTPStatus
@@ -11,40 +10,8 @@ from RangeHTTPServer import RangeRequestHandler
 
 class TestRequestHandler(RangeRequestHandler):
     def __init__(self, *args, **kwargs):
-        # NOTE: `directory` was introduced in 3.7
-        if sys.version_info < (3, 7):
-            self.directory = kwargs.pop("directory", None) or os.getcwd()
         super().__init__(*args, **kwargs)
 
-    def translate_path(self, path):
-        import posixpath
-        import urllib
-
-        # NOTE: `directory` was introduced in 3.7
-        if sys.version_info >= (3, 7):
-            return super().translate_path(path)
-
-        path = path.split("?", 1)[0]
-        path = path.split("#", 1)[0]
-        # Don't forget explicit trailing slash when normalizing. Issue17324
-        trailing_slash = path.rstrip().endswith("/")
-        try:
-            path = urllib.parse.unquote(path, errors="surrogatepass")
-        except UnicodeDecodeError:
-            path = urllib.parse.unquote(path)
-        path = posixpath.normpath(path)
-        words = path.split("/")
-        words = filter(None, words)
-        path = self.directory
-        for word in words:
-            if os.path.dirname(word) or word in (os.curdir, os.pardir):
-                # Ignore components that are not a simple file/directory name
-                continue
-            path = os.path.join(path, word)
-        if trailing_slash:
-            path += "/"
-        return path
-
     def end_headers(self):
         # RangeRequestHandler only sends Accept-Ranges header if Range header
         # is present, see https://github.com/danvk/RangeHTTPServer/issues/23