pazpar2: restore proper test

This was removed in dacab63 as running pazpar2
with the -t option caused a crash at the time.

This issue has been fixed in pazpar2 by now, so we
can restore the test we previously had.

Closes #8459.

Signed-off-by: Tomasz Pajor <tomek@polishgeeks.com>

Formula/pazpar2.rb

@@ -30,6 +30,16 @@ def install
   end
 
   test do
-    system "#{sbin}/pazpar2", "-V"
+    (testpath/"test-config.xml").write <<-EOS.undent
+    <?xml version="1.0" encoding="UTF-8"?>
+    <pazpar2 xmlns="http://www.indexdata.com/pazpar2/1.0">
+      <threads number="2"/>
+      <server>
+        <listen port="8004"/>
+      </server>
+    </pazpar2>
+    EOS
+
+    system "#{sbin}/pazpar2", "-t", "-f", "#{testpath}/test-config.xml"
   end
 end