component/tig: version up 2.5.4

I could not find tarball for 2.1 so I updated

component/tig/buildout.cfg

 # Tig: text-mode interface for Git
-# http://jonas.nitro.dk/tig/
+# https://jonas.github.io/tig/
 
 [buildout]
 extends =
+  ../libiconv/buildout.cfg
   ../ncurses/buildout.cfg
 
 [tig]
 recipe = slapos.recipe.cmmi
 shared = true
-url = http://jonas.nitro.dk/tig/releases/tig-2.1.tar.gz
-md5sum = d6c237aba2c03d85897da79789fd6104
+url = https://github.com/jonas/tig/releases/download/tig-2.5.5/tig-2.5.5.tar.gz
+md5sum = 0902ba706e8efaf6c2087d8b66393375
 environment =
-  CFLAGS=-I${ncurses:location}/include
-  LDFLAGS=-L${ncurses:location}/lib -Wl,-rpath=${ncurses:location}/lib
+  CFLAGS=-I${ncurses:location}/include -I${libiconv:location}/include
+  LDFLAGS=-L${ncurses:location}/lib -Wl,-rpath=${ncurses:location}/lib -L${libiconv:location}/lib -Wl,-rpath=${libiconv:location}/lib