Bump isort from 4.3.21 to 5.4.2 in /requirements

Bumps [isort](https://github.com/timothycrosley/isort) from 4.3.21 to 5.4.2.
- [Release notes](https://github.com/timothycrosley/isort/releases)
- [Changelog](https://github.com/PyCQA/isort/blob/develop/CHANGELOG.md)
- [Commits](PyCQA/isort@4.3.21...5.4.2)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements/requirements-ci.txt

@@ -74,7 +74,7 @@ iniconfig==1.0.1          # via -r requirements-dev.txt, pytest
 ipfshttpclient==0.6.0.post1  # via -r requirements-dev.txt, web3
 ipython-genutils==0.2.0   # via -r requirements-dev.txt, traitlets
 ipython==7.17.0           # via -r requirements-dev.txt
-isort==4.3.21             # via -r requirements-dev.txt, pylint
+isort==5.4.2              # via -r requirements-dev.txt, pylint
 itsdangerous==1.1.0       # via -r requirements-dev.txt, flask
 jedi==0.17.0              # via -r requirements-dev.txt, ipython
 jinja2==2.10.1            # via -r requirements-dev.txt, flask, matrix-synapse, sphinx

requirements/requirements-dev.txt

@@ -73,7 +73,7 @@ iniconfig==1.0.1          # via pytest
 ipfshttpclient==0.6.0.post1  # via -r requirements.txt, web3
 ipython-genutils==0.2.0   # via traitlets
 ipython==7.17.0           # via -r requirements-dev.in
-isort==4.3.21             # via -r requirements-dev.in, pylint
+isort==5.4.2              # via -r requirements-dev.in, pylint
 itsdangerous==1.1.0       # via -r requirements.txt, flask
 jedi==0.17.0              # via ipython
 jinja2==2.10.1            # via -r requirements-docs.txt, -r requirements.txt, flask, matrix-synapse, sphinx