build.jl: Use 0.2.0.dev1

deps/build.jl

@@ -5,7 +5,7 @@ function install_miplearn()
     Conda.update()
     pip = joinpath(dirname(pyimport("sys").executable), "pip")
     isfile(pip) || error("$pip: invalid path")
-    run(`$pip install miplearn==0.2.0`)
+    run(`$pip install miplearn==0.2.0.dev1`)
 end
 
 install_miplearn()