TST/DEP: update minimal Python requirements

test/python_requirements.txt

@@ -1,13 +1,12 @@
-# note: version requirements are indicative and tests # should be able to run with
+# note: version requirements are indicative and tests should be able to run with
 # older versions of our dependencies, though it is not guaranteed.
 
-# minimally require last versions available for Python 2.7
-numpy>=1.16.6
-matplotlib>=2.2.5
-scipy>=1.2.3
-
-# note that no version of inifix supports Python older than 3.6
+# minimally require earliest versions available for Python 3.10
+numpy>=1.21.1
+matplotlib>=3.5.0
+scipy>=1.7.2
 inifix>=0.11.2
+
 pybind11 >= 3.0.4
 # To run the test suite, we can use pytest, mostly any version
 # 6.0 is the one available on system available on debian-11