py38: upgrade structlog (#26203)

requirements-base.txt

@@ -54,7 +54,7 @@ sentry-sdk>=1.0.0,<1.2.0
 snuba-sdk>=0.0.14,<1.0.0
 simplejson==3.17.2
 statsd==3.3
-structlog==17.1.0
+structlog==21.1.0
 symbolic==8.1.0
 toronado==0.1.0
 ua-parser==0.10.0

src/sentry/runner/initializer.py

@@ -229,8 +229,6 @@ def configure_structlog():
             structlog.stdlib.add_log_level,
             structlog.stdlib.PositionalArgumentsFormatter(),
             structlog.processors.format_exc_info,
-            structlog.processors.StackInfoRenderer(),
-            structlog.processors.UnicodeDecoder(),
         ],
     }