disable auto_update_conda (#243)

* disable auto_update_conda

* revert write file in build step

* config after installing conda

* use sys condarc

either .condarc or condarc-julia.yml should work, but it might be more clear to use .condarc in ROOTENV

* Revert "use sys condarc"

This reverts commit 49574be.

src/Conda.jl

@@ -227,6 +227,7 @@ https://github.com/JuliaPy/Conda.jl.
         if Sys.iswindows()
             run(Cmd(`$installer /S --no-shortcuts /NoRegistry=1 /AddToPath=0 /RegisterPython=0 /D=$PREFIX`, windows_verbatim=true))
         end
+        write("$PREFIX/condarc-julia.yml", "auto_update_conda: false")
     end
     if !isdir(prefix(env))
         create(env)