Unpin IPython, and remove some dependencies on it.

This makes it annoying to test whether IPython breaks IPykernel.
I'm almost always on IPython master branch and I'd like to know when/if
I break things.

Prompted by ipython/ipython#13252,
which is not breaking ipykernel, but it's better to decouple where we
can.

Author: Carreau

ipykernel/inprocess/tests/test_kernel.py

@@ -13,10 +13,10 @@
 from ipykernel.inprocess.manager import InProcessKernelManager
 from ipykernel.inprocess.ipkernel import InProcessKernel
 from ipykernel.tests.utils import assemble_output
-from IPython.testing.decorators import skipif_not_matplotlib
 from IPython.utils.io import capture_output
 
 
+
 def _init_asyncio_patch():
     """set default asyncio policy to be compatible with tornado
 
@@ -60,9 +60,9 @@ def setUp(self):
         self.kc.start_channels()
         self.kc.wait_for_ready()
 
-    @skipif_not_matplotlib
     def test_pylab(self):
         """Does %pylab work in the in-process kernel?"""
+        matplotlib = pytest.importorskip('matplotlib', reason='This test requires matplotlib')
         kc = self.kc
         kc.execute('%pylab')
         out, err = assemble_output(kc.get_iopub_msg)

ipykernel/tests/test_kernel.py

@@ -14,7 +14,7 @@
 import pytest
 from packaging import version
 
-from IPython.testing import decorators as dec, tools as tt
+from IPython.testing import tools as tt
 import IPython
 from IPython.paths import locate_profile
 
@@ -225,8 +225,8 @@ def test_save_history():
         assert 'b="abcþ"' in content
 
 
-@dec.skip_without('faulthandler')
 def test_smoke_faulthandler():
+    faulthadler = pytest.importorskip('faulthandler', reason='this test needs faulthandler')
     with kernel() as kc:
         # Note: faulthandler.register is not available on windows.
         code = '\n'.join([
@@ -296,8 +296,8 @@ def test_complete():
         assert completed.startswith(cell)
 
 
-@dec.skip_without('matplotlib')
 def test_matplotlib_inline_on_import():
+    pytest.importorskip('matplotlib', reason='this test requires matplotlib')
     with kernel() as kc:
         cell = '\n'.join([
             'import matplotlib, matplotlib.pyplot as plt',

setup.py

@@ -64,7 +64,7 @@ def run(self):
         'importlib-metadata<5;python_version<"3.8.0"',
         'argcomplete>=1.12.3;python_version<"3.8.0"',
         'debugpy>=1.0.0,<2.0',
-        'ipython>=7.23.1,<8.0',
+        'ipython>=7.23.1',
         'traitlets>=5.1.0,<6.0',
         'jupyter_client<8.0',
         'tornado>=4.2,<7.0',