fix(wasm): support pydantic v1.x fallback for pyodide compatibility

The pyodide WASM environment resolves Pydantic 1.x instead of 2.x, leading to an AttributeError on `model_dump`.

- Add `hasattr(spec, 'model_dump')` check in `emit_openapi_dict` to seamlessly fallback to `.dict()` for Pydantic v1.

- Update `OpenAPIBase` in `models.py` to dynamically configure Pydantic `model_config` (v2) or `class Config` (v1) based on the active runtime.

Author: SamuelMarks

.gitignore

@@ -169,3 +169,4 @@ celerybeat.pid
 /update_tests*.py
 /fix_*.py
 
+/test_pydantic_v1.py

src/openapi_client/models.py

@@ -3,16 +3,21 @@
 from __future__ import annotations
 
 from typing import Any, Union
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, VERSION as PYDANTIC_VERSION
 
 
 class OpenAPIBase(BaseModel):
     """OpenAPI OpenAPIBase model."""
 
-    model_config = ConfigDict(
-        extra="allow",
-        populate_by_name=True,
-    )
+    if PYDANTIC_VERSION.startswith("2"):
+        model_config = ConfigDict(
+            extra="allow",
+            populate_by_name=True,
+        )
+    else:
+        class Config:
+            extra = "allow"
+            allow_population_by_field_name = True
 
 
 class Contact(OpenAPIBase):

src/openapi_client/openapi/emit.py

@@ -12,7 +12,9 @@
 
 def emit_openapi_dict(spec: OpenAPI) -> dict[str, Any]:
     """Emit an OpenAPI model as a dictionary."""
-    return spec.model_dump(by_alias=True, exclude_none=True)
+    if hasattr(spec, "model_dump"):
+        return spec.model_dump(by_alias=True, exclude_none=True)
+    return spec.dict(by_alias=True, exclude_none=True)
 
 
 def emit_openapi_json(spec: OpenAPI, indent: int = 2) -> str: