**Description:**
When PR body is empty `get_pull_request` method fails with bellow
exception.
**Issue:**
```
TypeError('expected string or buffer')Traceback (most recent call last):
File ".../.venv/lib/python3.9/site-packages/langchain_core/tools/base.py", line 661, in run
response = context.run(self._run, *tool_args, **tool_kwargs)
File ".../.venv/lib/python3.9/site-packages/langchain_community/tools/github/tool.py", line 52, in _run
return self.api_wrapper.run(self.mode, query)
File ".../.venv/lib/python3.9/site-packages/langchain_community/utilities/github.py", line 816, in run
return json.dumps(self.get_pull_request(int(query)))
File ".../.venv/lib/python3.9/site-packages/langchain_community/utilities/github.py", line 495, in get_pull_request
add_to_dict(response_dict, "body", pull.body)
File ".../.venv/lib/python3.9/site-packages/langchain_community/utilities/github.py", line 487, in add_to_dict
tokens = get_tokens(value)
File ".../.venv/lib/python3.9/site-packages/langchain_community/utilities/github.py", line 483, in get_tokens
return len(tiktoken.get_encoding("cl100k_base").encode(text))
File "....venv/lib/python3.9/site-packages/tiktoken/core.py", line 116, in encode
if match := _special_token_regex(disallowed_special).search(text):
TypeError: expected string or buffer
```
**Twitter:** __gorros__
f97ac92f00