CI: run 'make check' before 'make install'.

This makes sure 'make check' works when iverilog isn't already
installed on the system.

.github/workflows/test.yml

@@ -26,12 +26,12 @@ jobs:
         sudo apt update -qq
         sudo apt install -y make g++ git bison flex gperf libreadline-dev autoconf
 
-    - name: Build, install and check
+    - name: Build, check and install
       run: |
         autoconf
         ./configure
-        sudo make install
         make check
+        sudo make install
 
     - name: Test
       run: ./.github/test.sh