msi/tests: Write-strings warning fix.

dlls/msi/tests/install.c

@@ -694,7 +694,7 @@ static void test_packagecoltypes(void)
 {
     MSIHANDLE hdb, view, rec;
     char path[MAX_PATH];
-    LPSTR query;
+    LPCSTR query;
     UINT r, count;
 
     CoInitialize(NULL);