Run apt-get update before apt-get install

Switch from apt install to apt-get install, may avoid:

```
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
```

Author: jeremyevans

.github/workflows/test.yml

@@ -18,7 +18,8 @@ jobs:
         ruby-version: ${{ matrix.ruby }}
     - name: Install dependencies
       run: |
-        sudo apt install tk-dev
+        sudo apt-get update
+        sudo apt-get install tk-dev
         gem install bundler --no-document
         bundle install
     - name: Run test