docs: fixing multiple typos

Merge https://github.com/google/adk-python/pull/4221

### Link to Issue or Description of Change

N/A

**2. Or, if no issue exists, describe the change:**

Fixing various typos in .py files to improve quality: see commit diffs for details

**Problem:**

See above

**Solution:**
Fixing the typos

### Testing Plan

N/A

**Unit Tests:**

N/A

**Manual End-to-End (E2E) Tests:**

N/A

### Checklist

- [X] I have read the [CONTRIBUTING.md](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) document.
- [X] I have performed a self-review of my own code.
- [N/A] I have commented my code, particularly in hard-to-understand areas.
- [N/A ] I have added tests that prove my fix is effective or that my feature works.
- [N/A] New and existing unit tests pass locally with my changes.
- [N/A] I have manually tested my changes end-to-end.
- [N/A ] Any dependent changes have been merged and published in downstream modules.

### Additional context

N/A

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/4221 from didier-durand:fix-typos-e 1bcc8e05cdc116451222dd7fd7b0657745f769c1
PiperOrigin-RevId: 859332402

tests/unittests/models/test_litellm.py

@@ -10,7 +10,7 @@
 # distributed under the License is distributed on an "AS IS" BASIS,
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
-# limitations under the Licens
+# limitations under the License
 
 import contextlib
 import json

tests/unittests/runners/test_runner_rewind.py

@@ -130,14 +130,14 @@ class TestRunnerRewind:
         rewind_before_invocation_id="invocation2",
     )
 
-    # 3. Verify state and artifacts are rewinded
+    # 3. Verify state and artifacts are rewound
     session = await runner.session_service.get_session(
         app_name=runner.app_name, user_id=user_id, session_id=session_id
     )
     # After rewind before invocation2, only event1 state delta should apply.
     assert session.state["k1"] == "v1"
     assert not session.state["k2"]
-    # f1 should be rewinded to v0
+    # f1 should be rewound to v0
     assert await runner.artifact_service.load_artifact(
         app_name=runner.app_name,
         user_id=user_id,
@@ -226,7 +226,7 @@ class TestRunnerRewind:
         rewind_before_invocation_id="invocation3",
     )
 
-    # 3. Verify state and artifacts are rewinded
+    # 3. Verify state and artifacts are rewound
     session = await runner.session_service.get_session(
         app_name=runner.app_name, user_id=user_id, session_id=session_id
     )