Bump Hex Elixir version to 1.16.3

This bumps Elixir to the last version of 1.16.

A couple quirks:
1. `Mix.Dep.load_on_environment/1` is gone, but under the hood it called `Mix.Dep.Converger.converge/1`anyways.
2. Charlist dependencies explicitly fail now, and I'm fairly sure they should be updated if charlists are still used.

hex/Dockerfile

@@ -15,8 +15,8 @@ RUN apt-get update \
 
 # Install Elixir
 # https://github.com/elixir-lang/elixir/releases
-ARG ELIXIR_VERSION=v1.15.8
-ARG ELIXIR_CHECKSUM=62d33c51417191e027c9b6f0c46e11daeb236a7dda6f0746ec4dd53263531092
+ARG ELIXIR_VERSION=v1.16.3
+ARG ELIXIR_CHECKSUM=e8e81771bc6acd62a2c1bf1b31c3aa3d0a469415de3b243b99f3e2e2d639f5ea
 RUN curl -sSLfO https://github.com/elixir-lang/elixir/releases/download/${ELIXIR_VERSION}/elixir-otp-${ERLANG_MAJOR_VERSION}.zip \
   && echo "$ELIXIR_CHECKSUM  elixir-otp-${ERLANG_MAJOR_VERSION}.zip" | sha256sum -c - \
   && unzip -d /usr/local/elixir -x elixir-otp-${ERLANG_MAJOR_VERSION}.zip \

hex/helpers/lib/parse_deps.exs

@@ -3,7 +3,7 @@ defmodule Parser do
     # This is necessary because we can't specify :extra_applications to have :hex in other mixfiles.
     Mix.ensure_application!(:hex)
 
-    Mix.Dep.load_on_environment([])
+    Mix.Dep.Converger.converge()
     |> Enum.flat_map(&parse_dep/1)
     |> Enum.map(&build_dependency(&1.opts[:lock], &1))
   end

hex/spec/dependabot/hex/file_parser_spec.rb

@@ -255,8 +255,8 @@
       end
 
       context "with a tag (rather than a ref)" do
-        let(:mixfile_fixture_name) { "git_source_with_charlist" }
-        let(:lockfile_fixture_name) { "git_source_with_charlist" }
+        let(:mixfile_fixture_name) { "git_source_tag_can_update" }
+        let(:lockfile_fixture_name) { "git_source_tag_can_update" }
 
         it "includes the git dependency" do
           expect(dependencies.length).to eq(2)
@@ -476,7 +476,7 @@
       it "returns the correct language" do
         expect(language.name).to eq "elixir"
         expect(language.requirement).to be_nil
-        expect(language.version.to_s).to eq "1.15.8"
+        expect(language.version.to_s).to eq "1.16.3"
       end
     end
   end

hex/spec/dependabot/hex/update_checker/file_preparer_spec.rb

@@ -204,17 +204,6 @@
             'ref: "v1.2.1"}'
           )
         end
-
-        context "when there are single quotes" do
-          let(:mixfile_fixture_name) { "git_source_with_charlist" }
-
-          it "updates the pin" do
-            expect(prepared_mixfile.content).to include(
-              '{:phoenix, ">= 0", github: "dependabot-fixtures/phoenix", ' \
-              "ref: 'v1.2.1'}"
-            )
-          end
-        end
       end
     end