fix: declare `emqx_schema_registry` as a dependency of `emqx_schema_validation`

apps/emqx_schema_registry/src/emqx_schema_registry.app.src

@@ -11,7 +11,8 @@
         stdlib,
         erlavro,
         gpb,
-        jesse
+        jesse,
+        emqx
     ]},
     {env, []},
     {modules, []},

apps/emqx_schema_validation/src/emqx_schema_validation.app.src

@@ -5,7 +5,8 @@
     {mod, {emqx_schema_validation_app, []}},
     {applications, [
         kernel,
-        stdlib
+        stdlib,
+        emqx_schema_registry
     ]},
     {env, []},
     {modules, []},