Smoke tests for assorted plugins (#7721)

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>
Co-authored-by: Thomas Grainger <tagrain@gmail.com>
Co-authored-by: Kyle Altendorf <sda@fstab.net>

.github/workflows/main.yml

@@ -41,6 +41,7 @@ jobs:
 
           "docs",
           "doctesting",
+          "plugins",
         ]
 
         include:
@@ -111,6 +112,11 @@ jobs:
             tox_env: "py38-xdist"
             use_coverage: true
 
+          - name: "plugins"
+            python: "3.7"
+            os: ubuntu-latest
+            tox_env: "plugins"
+
           - name: "docs"
             python: "3.7"
             os: ubuntu-latest