fix appveyor builds - ant version changed to 1.9.8
diff --git a/appveyor.yml b/appveyor.yml
index 03ee295..e7ab87d 100755
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -30,7 +30,7 @@
   BOOST_ROOT: C:\Libraries\boost_1_59_0
   BOOST_LIBRARYDIR: C:\Libraries\boost_1_59_0\lib64-msvc-14.0
   # Unfurtunately, this version needs manual update because old versions are quickly deleted.
-  ANT_VERSION: 1.9.7
+  ANT_VERSION: 1.9.8
 
 install:
 - '"C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x64'