* .github/workflows/linux.yml: Perform `apt-get update` before `apt-get install`.

git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1909245 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index ed7cb76..796afce 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -15,8 +15,10 @@
 
     steps:
       - name: Install prerequisites
-        run: sudo apt-get install scons libapr1 libapr1-dev libaprutil1 libaprutil1-dev zlib1g zlib1g-dev libssl-dev
-  
+        run: |
+          sudo apt-get update
+          sudo apt-get install scons libapr1 libapr1-dev libaprutil1 libaprutil1-dev zlib1g zlib1g-dev libssl-dev
+
       - uses: actions/checkout@v3
 
       - name: Build