[requirements-dev.txt]: Update flake8

Update flake8 from `>=6.0, <8.0` to `>=7.0, <8.0`.

Author: andthum

requirements-dev.txt

@@ -7,7 +7,7 @@
 
 bandit[toml] >=1.0, <2.0
 black >=23.0, <24.0
-flake8 >=6.0, <8.0
+flake8 >=7.0, <8.0
 flake8-bandit >=4.0, <5.0
 flake8-bugbear >=23.0, <24.0
 flake8-builtins >=2.0, <3.0