Merge pull request #247 from remicollet/patch-1

Zstd 1.3.6 is enough

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index df55af1..8611a40 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -196,7 +196,7 @@
 endif(ENABLE_LZMA)
 
 if(ENABLE_ZSTD)
-  find_package(Zstd 1.5)
+  find_package(Zstd 1.3.6)
   if(Zstd_FOUND)
     set(HAVE_LIBZSTD 1)
   else()