Update links to 1.4-dev docs. (#32999)

Author: fredrikekre

doc/make.jl

@@ -210,8 +210,8 @@ withenv(env_mappings...) do
         repo = "github.com/JuliaLang/docs.julialang.org.git",
         target = joinpath(buildroot, "doc", "_build", "html", "en"),
         dirname = "en",
-        devurl = "v1.3-dev",
-        versions = ["v#.#", "v1.3-dev" => "v1.3-dev"]
+        devurl = "v1.4-dev",
+        versions = ["v#.#", "v1.4-dev" => "v1.4-dev"]
     )
 end
 end