Bump pip-tools from 5.5.0 to 6.0.1

Bumps [pip-tools](https://github.com/jazzband/pip-tools) from 5.5.0 to 6.0.1.
- [Release notes](https://github.com/jazzband/pip-tools/releases)
- [Changelog](https://github.com/jazzband/pip-tools/blob/master/CHANGELOG.md)
- [Commits](jazzband/pip-tools@5.5.0...6.0.1)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements/dev.txt

@@ -4,27 +4,25 @@
 #
 #    pip-compile --output-file=requirements/dev.txt requirements/dev.in
 #
-atomicwrites==1.4.0
-    # via pytest
 attrs==20.3.0
     # via pytest
 click==7.1.2
     # via pip-tools
-colorama==0.4.4
-    # via pytest
 coverage==5.4
     # via pytest-cov
 iniconfig==1.1.1
     # via pytest
 packaging==20.8
     # via pytest
-pip-tools==5.5.0
+pep517==0.10.0
+    # via pip-tools
+pip-tools==6.0.1
     # via -r requirements/dev.in
 pluggy==0.13.1
     # via pytest
 py==1.10.0
     # via pytest
-pylibmc==1.6.1; platform_system != 'Windows'
+pylibmc==1.6.1
     # via -r requirements/dev.in
 pyparsing==2.4.7
     # via packaging
@@ -39,7 +37,9 @@ python-memcached==1.59
 six==1.15.0
     # via python-memcached
 toml==0.10.2
-    # via pytest
+    # via
+    #   pep517
+    #   pytest
 
 # The following packages are considered to be unsafe in a requirements file:
 # pip