Replace codecov with coverage ci

Signed-off-by: Theofilos Manitaras <manitaras@cscs.ch>

Author: Theofilos Manitaras

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
     - name: Generic Unittests and Coverage Report
       if:  matrix.python-version == '3.8'
       run: |
-        pip install codecov
+        python -m pip install coverage
         coverage run --source=reframe ./test_reframe.py
         coverage report -m
     - name: Upload Coverage to Codecov

requirements.txt

@@ -1,7 +1,5 @@
 archspec==0.2.0
 argcomplete==2.0.0
-coverage==6.2; python_version < '3.7'
-coverage==7.1.0; python_version >= '3.7'
 importlib_metadata==4.0.1; python_version < '3.8'
 jsonschema==3.2.0
 lxml==4.9.2