Test gpytorch only with torch version 1.9 and up (#827)

Also, remove some obsolete excluded versions from CI.

.github/workflows/testing.yml

@@ -16,13 +16,9 @@ jobs:
     strategy:
       matrix:
         python_version: ['3.6', '3.7', '3.8', '3.9']
-        torch_version: ['1.7.1+cpu', '1.8.1+cpu', '1.9.1+cpu', '1.10.0+cpu']
+        torch_version: ['1.7.1+cpu', '1.8.1+cpu', '1.9.1+cpu', '1.10.1+cpu']
         os: [ubuntu-latest]
         exclude:
-          - python_version: '3.9'
-            torch_version: '1.5.1+cpu'
-          - python_version: '3.9'
-            torch_version: '1.6.0+cpu'
           - python_version: '3.9'
             torch_version: '1.7.1+cpu'
 

skorch/tests/test_net.py

@@ -1756,10 +1756,9 @@ def test_repr_initialized_works(self, net_cls, module_cls):
     )
   ),
 )"""
-        if LooseVersion(torch.__version__) >= '1.2':
-            expected = expected.replace("Softmax()", "Softmax(dim=-1)")
-            expected = expected.replace("Dropout(p=0.5)",
-                                        "Dropout(p=0.5, inplace=False)")
+        expected = expected.replace("Softmax()", "Softmax(dim=-1)")
+        expected = expected.replace("Dropout(p=0.5)",
+                                    "Dropout(p=0.5, inplace=False)")
         assert result == expected
 
     def test_repr_fitted_works(self, net_cls, module_cls, data):

skorch/tests/test_probabilistic.py

@@ -21,8 +21,10 @@
 
 # extract pytorch version without possible '+something' suffix
 pytorch_version, _, _ = torch.__version__.partition('+')
-if LooseVersion(pytorch_version) == '1.7.1':
-    pytest.skip("gpytorch does not work with PyTorch 1.7.1", allow_module_level=True)
+# Keep up to date with the gpytorch's supported versions:
+# https://github.com/cornellius-gp/gpytorch#installation
+if LooseVersion(pytorch_version) < '1.9':
+    pytest.skip("gpytorch does not support PyTorch versions < 1.9", allow_module_level=True)
 
 
 def get_batch_size(dist):