chore: remove extra target triplets (#322)

Signed-off-by: Cocoa <i@uwucocoa.moe>

Author: cocoa-xu

mix.exs

@@ -145,10 +145,7 @@ defmodule Exqlite.MixProject do
           :include_default_ones => true,
           "x86_64-linux-musl" => "x86_64-linux-musl-",
           "aarch64-linux-musl" => "aarch64-linux-musl-",
-          "riscv64-linux-musl" => "riscv64-linux-musl-",
-          "x86_64-linux-gnu" => "x86_64-linux-gnu-",
-          "aarch64-linux-gnu" => "aarch64-linux-gnu-",
-          "riscv64-linux-gnu" => "riscv64-linux-gnu-"
+          "riscv64-linux-musl" => "riscv64-linux-musl-"
         },
         {:unix, :darwin} => %{
           :include_default_ones => true