Add trimja-action

Add trimja-action to install, setup, and use trimja to reduce the
amount of work needed to do on CI.

We have to remove the `npm run docs` part as this depends on building
part of the project, which may have been removed with trimja.  We should
add an option to trimja-action to be able to include additional affected
entries and then we can pass `prep-for-docs` too.

.github/workflows/ci.yaml

@@ -25,8 +25,10 @@ jobs:
     - uses: seanmiddleditch/gha-setup-ninja@master
     - run: cd configure && npm ci
     - run: npm run configure
+    - uses: elliotgoodrich/trimja-action@6249b6da51a4cb9700ee01a850713a67009a3309
+      with:
+        version: '0.3.0'
     - run: ninja -k 0
-    - run: npm run docs
 
   deploy:
     needs: build