Failed to parse json credential

### [READ] Step 1: Are you in the right place?

* For issues related to __the code in this repository__ file a GitHub issue.
* If the issue pertains to __Cloud Firestore__, report directly in the
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* For general technical questions, post a question on [StackOverflow](http://stackoverflow.com/)
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### [REQUIRED] Step 2: Describe your environment

* Operating System version: MacOS Sonoma 14.3.1
* Firebase SDK version: 6.5.0
* Firebase Product: auth
* Python version: 3.11.0
* Pip version: 24.0

### [REQUIRED] Step 3: Describe the problem

When calling `firebase_admin.credentials.Certificate`, occurred error `OSError`, which used not credential file path, but parsed json dictionary. I expect returning function `_is_file_path` `False` if used parameter as dictionary.

#### Steps to reproduce:

What happened? How can we make the problem occur?
This could be a description, log/console output, etc.

#### Relevant Code:

```
# firebase_admin/credentials.py
def _is_file_path(path):
try:
path_obj = pathlib.Path(path)
return True
except TypeError:
return False
```

Start in firebase_admin/credentials.py at _is_file_path and inspect how Certificate handles a parsed JSON dictionary versus a credential file path. Reproduce the reported OSError with the issue's environment details, then verify that dictionary credentials are recognized correctly without breaking path handling.

Written by the indexing model from the issue text.