Added markupsafe==2.0.1 to dev requirements. Newer versions of it break.

Signed-off-by: Md Safiyat Reza <[email protected]>

assets/requirements-dev.txt

@@ -3,7 +3,8 @@ bandit>=1.6.2,<1.7.0
 bs4>=0.0.1,<0.1.0
 commitizen>=0.9.11,<1.17.0
 isort>=4.3.21,<4.4.0
-flake8>=3.7.9,<3.8.0s
+flake8>=3.7.9,<3.8.0
+markupsafe==2.0.1
 mock>=3.0.5,<3.1.0
 pytest>=4.6.9,<5.3.0
 pytest-cov>=2.8.1,<2.9.0