Drop testing with poetry<2

due to complication as a result of drastic change in pyproject syntax

Author: monim67

tests/pip-constraints.txt

@@ -1,5 +1 @@
-poetry>=1.7 ; python_version >= "3.12"
-poetry>=1.6,<1.7 ; python_version >= "3.11" and python_version < "3.12"
-poetry>=1.5,<1.6 ; python_version >= "3.10" and python_version < "3.11"
-poetry>=1.4,<1.5 ; python_version >= "3.9" and python_version < "3.10"
-poetry>=1.2,<1.3 ; python_version >= "3.8" and python_version < "3.9"
+poetry>=2.0 ; python_version >= "3.9"