Update the minimum Python version for JPype1 <= 1.0.1

It was found that all versions of JPype <=1.0.1 are incompatible with Python >=3.8.4. We therefore mark the dependencies clearly. The intention is that this will likely be the last release to support v0.6 of JPype1, and ideally we will cease supporting v0.7 soon after.

setup.py

@@ -17,7 +17,11 @@ with (HERE / 'README.md').open('rt') as fh:
 REQUIREMENTS: dict = {
     'core': [
         'entrypoints',
-        'JPype1>=0.6.1',
+
+        # Older versions of JPype1 do not work in Python 3.8+
+        # https://github.com/jpype-project/jpype/pull/788
+        'JPype1>=1.0.1;python_version>="3.8.4"',
+        'JPype1>=0.6.1;python_version<"3.8.4"',
         'requests',
         'six',
     ],
@@ -38,7 +42,7 @@ setup(
     license='MIT',
     url='https://gitlab.cern.ch/scripting-tools/cmmnbuild-dep-manager',
     packages=find_packages(),
-    python_requires='>=3.6, <4',
+    python_requires='~=3.6',
     classifiers=[
         "Programming Language :: Python :: 3",
         "Operating System :: OS Independent",