[roottest] Correct a fixture name for a schema evolution test.

The "readNew" test reads an old file with a new class definition. By
mistake, its fixture was however causing the creation of the root file
with the new class version that is used in a different test.

Author: hageboeck

roottest/root/io/evolution/CMakeLists.txt

@@ -60,7 +60,8 @@ ROOTTEST_ADD_TEST(ClassConvReadNew
                   MACRO ClassConvReadNew.cxx
                   OUTREF ClassConvReadNew.ref
                   LABELS longtest io
-                  FIXTURES_REQUIRED root-io-evolution-ClassConvWriteNew-fixture)
+                  FIXTURES_REQUIRED root-io-evolution-ClassConvWriteOld-fixture # Not a typo. It reads the old file
+                  )
 
 
 ROOTTEST_COMPILE_MACRO(ClassConvOther.cxx