fix(types): Align FlagsmithProvider children prop type with React.ReactNode (#317)

Ensures the `children` prop in `FlagsmithProvider`'s type definition (`FlagsmithContextType`) is correctly set to `React.ReactNode` in both the implementation (`react.tsx`) and the declaration file (`react.d.ts`).

Adds a type test to verify that `FlagsmithProvider` compiles successfully when provided with a plain string child, which is a valid `React.ReactNode`. This test would fail compilation if the type were incorrectly restricted (e.g., to `ReactElement | ReactElement[]`).

Author: dreglad

react.d.ts

@@ -6,7 +6,7 @@ export declare type FlagsmithContextType<F extends string = string, T extends st
     flagsmith: IFlagsmith<F, T>;
     options?: Parameters<IFlagsmith<F, T>['init']>[0];
     serverState?: IState;
-    children: React.ReactElement[] | React.ReactElement;
+    children: React.ReactNode;
 };
 type UseFlagsReturn<
     F extends string | Record<string, any>,

test/react-types.test.tsx

@@ -122,4 +122,15 @@ describe.only('FlagsmithProvider', () => {
             </FlagsmithProvider>
         );
     });
+    it('should compile if children prop is React.ReactNode', () => {
+        const { flagsmith, initConfig } = getFlagsmith();
+        const children: React.ReactNode = "I am a ReactNode child";
+        const { container } = render(
+            <FlagsmithProvider flagsmith={flagsmith} options={initConfig}>
+                {children}
+            </FlagsmithProvider>
+        );
+
+        expect(container.textContent).toBe(children);
+    });
 });