CLI script to gather environment info (#2699)

* add "info" command to CLI

As a convenience, add the info directive to CLI. Running `python transformers-cli info` will return a string containing the transformers version, platform, python version, PT/TF version and GPU support

* Swap f-strings for .format

Still supporting 3.5 so can't use f-strings (sad face)

* Add reference in issue to CLI

* Add the expected fields to issue template

This way, people can still add the information manually if they want. (Though I fear they'll just ignore it.)

* Remove heading from output

* black-ify

* order of imports

Should ensure isort test passes

* use is_X_available over import..pass

* style

* fix copy-paste bug

* Rename command info -> env

Also adds the command to CONTRIBUTING.md in "Did you find a bug" section

src/transformers/commands/env.py

@@ -0,0 +1,58 @@
+import platform
+from argparse import ArgumentParser
+
+from transformers import __version__ as version
+from transformers import is_tf_available, is_torch_available
+from transformers.commands import BaseTransformersCLICommand
+
+
+def info_command_factory(_):
+    return EnvironmentCommand()
+
+
+class EnvironmentCommand(BaseTransformersCLICommand):
+    @staticmethod
+    def register_subcommand(parser: ArgumentParser):
+        download_parser = parser.add_parser("env")
+        download_parser.set_defaults(func=info_command_factory)
+
+    def run(self):
+        pt_version = "not installed"
+        pt_cuda_available = "NA"
+        if is_torch_available():
+            import torch
+
+            pt_version = torch.__version__
+            pt_cuda_available = torch.cuda.is_available()
+
+        tf_version = "not installed"
+        tf_cuda_available = "NA"
+        if is_tf_available():
+            import tensorflow as tf
+
+            tf_version = tf.__version__
+            try:
+                # deprecated in v2.1
+                tf_cuda_available = tf.test.is_gpu_available()
+            except AttributeError:
+                # returns list of devices, convert to bool
+                tf_cuda_available = bool(tf.config.list_physical_devices("GPU"))
+
+        info = {
+            "`transformers` version": version,
+            "Platform": platform.platform(),
+            "Python version": platform.python_version(),
+            "PyTorch version (GPU?)": "{} ({})".format(pt_version, pt_cuda_available),
+            "Tensorflow version (GPU?)": "{} ({})".format(tf_version, tf_cuda_available),
+            "Using GPU in script?": "<fill in>",
+            "Using distributed or parallel set-up in script?": "<fill in>",
+        }
+
+        print("\nCopy-and-paste the text below in your GitHub issue and FILL OUT the two last points.\n")
+        print(self.format_dict(info))
+
+        return info
+
+    @staticmethod
+    def format_dict(d):
+        return "\n".join(["- {}: {}".format(prop, val) for prop, val in d.items()]) + "\n"