fireworks[patch]: fix api_key alias in Fireworks LLM (#23118)

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**Description**
The current code snippet for `Fireworks` had incorrect parameters. This
PR fixes those parameters.

---------

Co-authored-by: Chester Curme <chester.curme@gmail.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/partners/fireworks/langchain_fireworks/llms.py

@@ -90,7 +90,7 @@ class Fireworks(LLM):
         )
         return values
 
-    @root_validator(pre=True)
+    @root_validator(pre=False, skip_on_failure=True)
     def validate_environment(cls, values: Dict) -> Dict:
         """Validate that api key exists in environment."""
         values["fireworks_api_key"] = convert_to_secret_str(

libs/partners/fireworks/tests/unit_tests/test_llms.py

@@ -18,6 +18,15 @@ def test_fireworks_api_key_is_secret_string() -> None:
     )
     assert isinstance(llm.fireworks_api_key, SecretStr)
 
+    # Test api_key alias
+    llm = Fireworks(
+        api_key="secret-api-key",
+        model="accounts/fireworks/models/mixtral-8x7b-instruct",
+        temperature=0.2,
+        max_tokens=250,
+    )
+    assert isinstance(llm.fireworks_api_key, SecretStr)
+
 
 def test_fireworks_api_key_masked_when_passed_from_env(
     monkeypatch: MonkeyPatch, capsys: CaptureFixture