build: Use toml defined dev dependencies over txt file (#17356)

* build: Use toml defined dev dependencies over txt file

* chore: Remove redundant ==

* ref: https://github.com/frappe/bench/releases/tag/v5.12.1
* Linter's style updates

* chore(deps): Bump coverage from 5.5 to ~=6.4.1

dev-requirements.txt

@@ -1,4 +0,0 @@
-coverage==5.5
-Faker~=13.12.1
-pyngrok~=5.0.5
-unittest-xml-reporting~=3.0.4

pyproject.toml

@@ -103,3 +103,9 @@ force_grid_wrap = 0
 use_parentheses = true
 ensure_newline_before_comments = true
 indent = "\t"
+
+[tool.bench.dev-dependencies]
+coverage = "~=6.4.1"
+Faker = "~=13.12.1"
+pyngrok = "~=5.0.5"
+unittest-xml-reporting = "~=3.0.4"