chore(tests): add missing pytest import in test_base_events

Signed-off-by: Yurii Serhiichuk <savik.ne@gmail.com>

Author: xSAVIKx

tests/test_v1_compat/test_base_events.py

@@ -12,6 +12,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import pytest
+
 import cloudevents.v1.exceptions as cloud_exceptions
 from cloudevents.v1.sdk.event import v03, v1