Fix post-Elixir 1.16 divergence in File.stream!

lib/philomena/sha512.ex

@@ -1,11 +1,27 @@
 defmodule Philomena.Sha512 do
-  @spec file(String.t()) :: String.t()
-  def file(file) do
+  @chunk_size 10_485_760
+
+  @spec file(Path.t()) :: String.t()
+  def file(path) do
     hash_ref = :crypto.hash_init(:sha512)
 
-    File.stream!(file, [], 10_485_760)
+    path
+    |> stream_file()
     |> Enum.reduce(hash_ref, &:crypto.hash_update(&2, &1))
     |> :crypto.hash_final()
     |> Base.encode16(case: :lower)
   end
+
+  if Version.match?(System.version(), ">= 1.16.0") do
+    # `stream!/2` was added in Elixir 1.16 to accept a shortened form,
+    # where we only need to specify the size of each stream chunk
+    defp stream_file(file) do
+      File.stream!(file, @chunk_size)
+    end
+  else
+    # Use legacy stream/3 for older Elixir versions
+    defp stream_file(file) do
+      File.stream!(file, [], @chunk_size)
+    end
+  end
 end