use latest Eigen (#49)

Author: koide3

CMakeLists.txt

@@ -43,11 +43,11 @@ endif()
 find_package(Eigen3 CONFIG)
 
 if(NOT Eigen3_FOUND)
-  message(STATUS "System Eigen not found. Download Eigen 3.3.9.")
+  message(STATUS "System Eigen not found. Download Eigen 3.4.0.")
   include(FetchContent)
   FetchContent_Populate(
     Eigen3
-    URL https://gitlab.com/libeigen/eigen/-/archive/3.3.9/eigen-3.3.9.tar.gz
+    URL https://gitlab.com/libeigen/eigen/-/archive/3.4.0/eigen-3.4.0.tar.gz
   )
   add_library(Eigen3::Eigen INTERFACE IMPORTED GLOBAL)
   set_target_properties(Eigen3::Eigen PROPERTIES