tests: try lexing example.yul, too.

Add it to tracking, too.

.gitlab-ci.yml

@@ -5,3 +5,4 @@ test:
     - pip install -r requirements.txt
     - pip install -e .
     - pygmentize example.sol
+    - pygmentize example.yul

example.yul

@@ -0,0 +1,15 @@
+{
+    // my function
+    function power(base, exponent) -> result
+    {
+        switch exponent
+        case 0 { result := 1 }
+        case 1 { result := base }
+        default
+        {
+            result := power(mul(base, base), div(exponent, 2))
+            switch mod(exponent, 2)
+                case 1 { result := mul(base, result) }
+        }
+    }
+}