chore: use ubuntu 18.04

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
   release:
     strategy:
       matrix:
-        os: [windows-latest, ubuntu-latest, macos-latest]
+        os: [windows-latest, ubuntu-18.04, macos-latest]
     runs-on: ${{ matrix.os }}
     if: |
       startsWith(github.repository, 'zzzgydi') &&
@@ -37,7 +37,7 @@ jobs:
           node-version: 14
 
       - name: Install Dependencies (ubuntu only)
-        if: matrix.os == 'ubuntu-latest'
+        if: startsWith(matrix.os, 'ubuntu-')
         run: |
           sudo apt-get update
           sudo apt-get install -y libwebkit2gtk-4.0-dev build-essential curl wget libssl-dev libgtk-3-dev libappindicator3-dev librsvg2-dev libayatana-appindicator3-dev