Make ci workflow depend on format workflow

Also, let Documenter workflow depend on ci workflow

Author: andreasnoack

.github/workflows/Documenter.yml

@@ -5,7 +5,10 @@ on:
     branches:
       - master
     tags: '*'
-  pull_request:
+  workflow_run:
+    workflows: ["ci"]
+    types:
+      - completed
 
 jobs:
   build:

.github/workflows/ci.yml

@@ -2,7 +2,10 @@ name: CI
 env:
   JULIA_NUM_THREADS: 2
 on:
-  pull_request:
+  workflow_run:
+    workflows: ["format"]
+    types:
+      - completed
   push:
     branches:
       - master