Pin flask-restx in flask_rest tests for 2.7

flask-restx dropped support for 2.7 in 1.0.1.

tox.ini

@@ -62,7 +62,8 @@ envlist =
     gearman-application_gearman-{py27,pypy},
     python-component_djangorestframework-py27-djangorestframework0300,
     python-component_djangorestframework-{py37,py38,py39,py310,py311}-djangorestframeworklatest,
-    python-component_flask_rest-{py27,py37,py38,py39,pypy,pypy37},
+    python-component_flask_rest-{py37,py38,py39,pypy37}-flaskrestxlatest,
+    python-component_flask_rest-{py27,pypy}-flaskrestx051,
     python-component_graphqlserver-{py37,py38,py39,py310,py311},
     python-component_tastypie-{py27,pypy}-tastypie0143,
     python-component_tastypie-{py37,py38,py39,pypy37}-tastypie{0143,latest},
@@ -208,9 +209,10 @@ deps =
     component_flask_rest: flask<0.13
     component_flask_rest: flask-restful
     component_flask_rest: flask-restplus
-    component_flask_rest: flask-restx
     component_flask_rest: jinja2<3.1
     component_flask_rest: itsdangerous<2.1
+    component_flask_rest-flaskrestxlatest: flask-restx
+    component_flask_rest-flaskrestx051: flask-restx<1.0
     component_graphqlserver: graphql-server[sanic,flask]==3.0.0b5
     component_graphqlserver: sanic>20
     component_graphqlserver: Flask