Bump pip-tools from 6.0.1 to 6.1.0

Bumps [pip-tools](https://github.com/jazzband/pip-tools) from 6.0.1 to 6.1.0.
- [Release notes](https://github.com/jazzband/pip-tools/releases)
- [Changelog](https://github.com/jazzband/pip-tools/blob/master/CHANGELOG.md)
- [Commits](jazzband/pip-tools@6.0.1...6.1.0)

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

requirements/dev.txt

@@ -4,25 +4,21 @@
 #
 #    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==5.5
     # via pytest-cov
 iniconfig==1.1.1
     # via pytest
-lxml==4.6.3; implementation_name != 'pypy'
+lxml==4.6.3
     # via -r requirements/dev.in
 packaging==20.9
     # via pytest
 pep517==0.10.0
     # via pip-tools
-pip-tools==6.0.1
+pip-tools==6.1.0
     # via -r requirements/dev.in
 pluggy==0.13.1
     # via pytest