Deprecate --flake8 in favor of --ruff and update documentation

Signed-off-by: jirka <6035284+Borda@users.noreply.github.com>

Author: Borda

CONTRIBUTING.md

@@ -37,7 +37,7 @@ Please note that, as per PyTorch, MONAI uses American English spelling. This mea
 
 ### Preparing pull requests
 
-To ensure the code quality, MONAI relies on several linting tools ([flake8 and its plugins](https://gitlab.com/pycqa/flake8), [black](https://github.com/psf/black), [isort](https://github.com/timothycrosley/isort), [ruff](https://github.com/astral-sh/ruff)),
+To ensure the code quality, MONAI relies on several linting tools ([black](https://github.com/psf/black), [isort](https://github.com/timothycrosley/isort), [ruff](https://github.com/astral-sh/ruff)),
 static type analysis tools ([mypy](https://github.com/python/mypy), [pytype](https://github.com/google/pytype)), as well as a set of unit/integration tests.
 
 This section highlights all the necessary preparation steps required before sending a pull request.
@@ -51,7 +51,7 @@ To collaborate efficiently, please read through this section and follow them.
 
 #### Checking the coding style
 
-Coding style is checked and enforced by flake8, black, isort, and ruff, using [a flake8 configuration](./setup.cfg) similar to [PyTorch's](https://github.com/pytorch/pytorch/blob/master/.flake8).
+Coding style is checked and enforced by black, isort, and ruff.
 Before submitting a pull request, we recommend that all linting should pass, by running the following command locally:
 
 ```bash

runtests.sh

@@ -81,6 +81,7 @@ function print_usage {
     echo "    --isort           : perform \"isort\" import sort checks"
     echo "    --pylint          : perform \"pylint\" code format checks"
     echo "    --ruff            : perform \"ruff\" code format checks"
+    echo "    --flake8          : perform \"ruff\" code format checks (deprecated alias for --ruff)"
     echo "    --clangformat     : format csrc code using \"clang-format\""
     echo "    --precommit       : perform source code format check and fix using \"pre-commit\""
     echo ""
@@ -302,6 +303,10 @@ do
         --ruff)
             doRuffFormat=true
         ;;
+        --flake8)
+            echo "${red}warning: --flake8 is deprecated, please use --ruff instead.${noColor}"
+            doRuffFormat=true
+        ;;
         --precommit)
             doPrecommit=true
         ;;