ci: Remove jsonschema from requirements-testing.txt (#6620)

Remove the package from `requirements-testing.txt` and add it only as a dependency of the test suites that rely on it.
This is part of environment cleanup before moving the remaining testing dependencies to a uv dependency group.

Author: alexander-alderman-webb

requirements-testing.txt

@@ -3,7 +3,6 @@ pytest-cov
 pytest-forked
 pytest-localserver
 pytest-timeout
-jsonschema
 executing
 asttokens
 responses

scripts/populate_tox/tox.jinja

@@ -80,6 +80,7 @@ deps =
     # === Common ===
     py3.8-common: hypothesis
     common: brotli
+    common: jsonschema
     common: pysocks
     common: pytest-asyncio
     common: httpcore[asyncio]
@@ -101,6 +102,7 @@ deps =
     {py3.6,py3.7}-gevent: pytest<7.0.0
     {py3.8,py3.9,py3.10,py3.11,py3.12}-gevent: pytest
     gevent: brotli
+    gevent: jsonschema
     gevent: pysocks
     gevent: pytest-asyncio
     gevent: setuptools<82

tests/conftest.py

@@ -18,7 +18,11 @@
 except ImportError:
     brotli = None
 
-import jsonschema
+try:
+    import jsonschema
+except ImportError:
+    jsonschema = None
+
 import pytest
 from pytest_localserver.http import WSGIServer
 from werkzeug.wrappers import Request, Response
@@ -236,6 +240,7 @@ def _capture_internal_warnings():
 @pytest.fixture
 def validate_event_schema(tmpdir):
     def inner(event):
+        assert jsonschema is not None
         if SENTRY_EVENT_SCHEMA:
             jsonschema.validate(instance=event, schema=SENTRY_EVENT_SCHEMA)