Add missing hyphen for tox factor

Author: ocelotl

tox.ini

@@ -88,9 +88,9 @@ envlist =
     pypy3-test-instrumentation-fastapi
 
     ; opentelemetry-instrumentation-flask
-    py3{7,8,9,10,11}-test-instrumentation-flask{0,1}
-    py3{8,9,10,11}-test-instrumentation-flask{2}
-    pypy3-test-instrumentation-flask{0,1}
+    py3{7,8,9,10,11}-test-instrumentation-flask-{0,1}
+    py3{8,9,10,11}-test-instrumentation-flask-{2}
+    pypy3-test-instrumentation-flask-{0,1}
 
     ; opentelemetry-instrumentation-urllib
     py3{7,8,9,10,11}-test-instrumentation-urllib