fix typo in cmake
Patch: Jens Geyer

This closes #1910
diff --git a/lib/hs/CMakeLists.txt b/lib/hs/CMakeLists.txt
index 1a5b8fd..c477c9b 100644
--- a/lib/hs/CMakeLists.txt
+++ b/lib/hs/CMakeLists.txt
@@ -37,7 +37,7 @@
 )
 
 if(BUILD_TESTING)
-    list(APPEND haskell_soruces
+    list(APPEND haskell_sources
         test/Spec.hs
         test/BinarySpec.hs
         test/CompactSpec.hs