fix: rename test module to tests

examples/acceptance_tests/032/lib/tests.ak

@@ -0,0 +1,15 @@
+fn is_negative(i: Int) -> Bool {
+  if i < 0 {
+    trace("is negative")
+
+  True
+  } else {
+    trace("is non-negative")
+
+  False
+  }
+}
+
+test trace_1() {
+  is_negative(-14) && !is_negative(42)
+}