Remove crypt(3) support

This was used to support migration from GNU Social, which was used by at least
shitposter.club, should be entirely irrelevant now.

Closes: https://git.pleroma.social/pleroma/pleroma/-/issues/3030
Closes: https://git.pleroma.social/pleroma/pleroma/-/issues/3062

test/pleroma/web/plugs/authentication_plug_test.exs

@@ -70,28 +70,6 @@ defmodule Pleroma.Web.Plugs.AuthenticationPlugTest do
     assert "$pbkdf2" <> _ = user.password_hash
   end
 
-  @tag :skip_on_mac
-  test "with a crypt hash, it updates to a pkbdf2 hash", %{conn: conn} do
-    user =
-      insert(:user,
-        password_hash:
-          "$6$9psBWV8gxkGOZWBz$PmfCycChoxeJ3GgGzwvhlgacb9mUoZ.KUXNCssekER4SJ7bOK53uXrHNb2e4i8yPFgSKyzaW9CcmrDXWIEMtD1"
-      )
-
-    conn =
-      conn
-      |> assign(:auth_user, user)
-      |> assign(:auth_credentials, %{password: "password"})
-      |> AuthenticationPlug.call(%{})
-
-    assert conn.assigns.user.id == conn.assigns.auth_user.id
-    assert conn.assigns.token == nil
-    assert PlugHelper.plug_skipped?(conn, OAuthScopesPlug)
-
-    user = User.get_by_id(user.id)
-    assert "$pbkdf2" <> _ = user.password_hash
-  end
-
   describe "checkpw/2" do
     test "check pbkdf2 hash" do
       hash =
@@ -101,14 +79,6 @@ defmodule Pleroma.Web.Plugs.AuthenticationPlugTest do
       refute AuthenticationPlug.checkpw("test-password1", hash)
     end
 
-    @tag :skip_on_mac
-    test "check sha512-crypt hash" do
-      hash =
-        "$6$9psBWV8gxkGOZWBz$PmfCycChoxeJ3GgGzwvhlgacb9mUoZ.KUXNCssekER4SJ7bOK53uXrHNb2e4i8yPFgSKyzaW9CcmrDXWIEMtD1"
-
-      assert AuthenticationPlug.checkpw("password", hash)
-    end
-
     test "check bcrypt hash" do
       hash = "$2a$10$uyhC/R/zoE1ndwwCtMusK.TLVzkQ/Ugsbqp3uXI.CTTz0gBw.24jS"