Merge branch 'patnala_issue_3_setup_test_environment' into 'main'

added requirements.txt and test file test_calculator.py

See merge request !3

requirements.txt

+coverage==7.2.6
+exceptiongroup==1.1.1
+iniconfig==2.0.0
+packaging==23.1
+pluggy==1.0.0
+pytest==7.3.1
+pytest-cov==4.0.0
+tomli==2.0.1

test_calculator.py

+import calculator
+
+class TestCalculator:
+
+    def test_add(self):
+        assert 4 == calculator.add(2,2)
+        assert 10 == calculator.add(3,7)