GitHub workflows: Install Node.js v12

I'm not sure how these tests ever worked. I guess some version of
Node.js and npm come pre-installed on the ubuntu-latest images?

I would have prefered to use Node.js v10 because that is our current
minimum supported version, but we have a surprising number of tests
that don't work on Node.js v10 (mostly due to `assert.match()`, which
was added in Node.js v12).

.github/workflows/backend-tests.yml

@@ -17,6 +17,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Install libreoffice
       run: |
         sudo add-apt-repository -y ppa:libreoffice/ppa
@@ -43,6 +47,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Install libreoffice
       run: |
         sudo add-apt-repository -y ppa:libreoffice/ppa

.github/workflows/frontend-admin-tests.yml

@@ -11,6 +11,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Run sauce-connect-action
       shell: bash
       env:

.github/workflows/frontend-tests.yml

@@ -11,6 +11,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Run sauce-connect-action
       shell: bash
       env:
@@ -47,6 +51,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Run sauce-connect-action
       shell: bash
       env:

.github/workflows/lint-package-lock.yml

@@ -17,6 +17,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Install lockfile-lint
       run: npm install lockfile-lint
 

.github/workflows/load-test.yml

@@ -17,6 +17,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Install all dependencies and symlink for ep_etherpad-lite
       run: src/bin/installDeps.sh
 
@@ -39,6 +43,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: Install etherpad-load-test
       run: sudo npm install -g etherpad-load-test
 

.github/workflows/rate-limit.yml

@@ -16,6 +16,10 @@ jobs:
     - name: Checkout repository
       uses: actions/checkout@v2
 
+    - uses: actions/setup-node@v2
+      with:
+        node-version: 12
+
     - name: docker network
       run: docker network create --subnet=172.23.42.0/16 ep_net