Arm backend: Only describe pytest and not python unittest in README.md (#9709)

Signed-off-by: Zingo Andersen <[email protected]>

Author: zingo

backends/arm/README.md

@@ -79,30 +79,12 @@ test                            #  Root test folder
 
 Some example commands to run these tests follow. Run a single test:
 
-```
-python -m unittest backends.arm.test.ops.test_add.TestSimpleAdd -k test_add2_tosa_BI
-```
-
-or with pytest
-
 ```
 pytest -c /dev/null -v -n auto backends/arm/test/ops/test_add.py -k test_add2_tosa_BI
 ```
 
-Or all tests in "TestSimpleAdd":
-
-```
-python -m unittest backends.arm.test.ops.test_add.TestSimpleAdd
-```
-
 Or discover and run many tests:
 
-```
-python -m unittest discover -s backends/arm/test/ops/
-```
-
-or with pytest
-
 ```
 pytest -c /dev/null -v -n auto backends/arm/test/ops/
 ```