Bump postgrex from 0.17.3 to 0.17.4 in /example

Bumps [postgrex](https://github.com/elixir-ecto/postgrex) from 0.17.3 to 0.17.4.
- [Release notes](https://github.com/elixir-ecto/postgrex/releases)
- [Changelog](https://github.com/elixir-ecto/postgrex/blob/master/CHANGELOG.md)
- [Commits](elixir-ecto/postgrex@v0.17.3...v0.17.4)

---
updated-dependencies:
- dependency-name: postgrex
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

example/mix.lock

@@ -24,7 +24,7 @@
   "plug": {:hex, :plug, "1.15.1", "b7efd81c1a1286f13efb3f769de343236bd8b7d23b4a9f40d3002fc39ad8f74c", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2 or ~> 2.0", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "459497bd94d041d98d948054ec6c0b76feacd28eec38b219ca04c0de13c79d30"},
   "plug_cowboy": {:hex, :plug_cowboy, "2.6.1", "9a3bbfceeb65eff5f39dab529e5cd79137ac36e913c02067dba3963a26efe9b2", [:mix], [{:cowboy, "~> 2.7", [hex: :cowboy, repo: "hexpm", optional: false]}, {:cowboy_telemetry, "~> 0.3", [hex: :cowboy_telemetry, repo: "hexpm", optional: false]}, {:plug, "~> 1.14", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "de36e1a21f451a18b790f37765db198075c25875c64834bcc82d90b309eb6613"},
   "plug_crypto": {:hex, :plug_crypto, "2.0.0", "77515cc10af06645abbfb5e6ad7a3e9714f805ae118fa1a70205f80d2d70fe73", [:mix], [], "hexpm", "53695bae57cc4e54566d993eb01074e4d894b65a3766f1c43e2c61a1b0f45ea9"},
-  "postgrex": {:hex, :postgrex, "0.17.3", "c92cda8de2033a7585dae8c61b1d420a1a1322421df84da9a82a6764580c503d", [:mix], [{:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "946cf46935a4fdca7a81448be76ba3503cff082df42c6ec1ff16a4bdfbfb098d"},
+  "postgrex": {:hex, :postgrex, "0.17.4", "5777781f80f53b7c431a001c8dad83ee167bcebcf3a793e3906efff680ab62b3", [:mix], [{:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "6458f7d5b70652bc81c3ea759f91736c16a31be000f306d3c64bcdfe9a18b3cc"},
   "ranch": {:hex, :ranch, "1.8.0", "8c7a100a139fd57f17327b6413e4167ac559fbc04ca7448e9be9057311597a1d", [:make, :rebar3], [], "hexpm", "49fbcfd3682fab1f5d109351b61257676da1a2fdbe295904176d5e521a2ddfe5"},
   "tailwind": {:hex, :tailwind, "0.2.2", "9e27288b568ede1d88517e8c61259bc214a12d7eed271e102db4c93fcca9b2cd", [:mix], [{:castore, ">= 0.0.0", [hex: :castore, repo: "hexpm", optional: false]}], "hexpm", "ccfb5025179ea307f7f899d1bb3905cd0ac9f687ed77feebc8f67bdca78565c4"},
   "telemetry": {:hex, :telemetry, "1.2.1", "68fdfe8d8f05a8428483a97d7aab2f268aaff24b49e0f599faa091f1d4e7f61c", [:rebar3], [], "hexpm", "dad9ce9d8effc621708f99eac538ef1cbe05d6a874dd741de2e689c47feafed5"},