Add Postgres 14.5 to test matrix

Relates to #112

.github/workflows/pull.yaml

@@ -20,7 +20,7 @@ jobs:
  # - ubuntu-latest (Ubuntu 22) mandates OTP >= 24
  # - dialyxir uses `Kernel.then` and hence mandates Elixir >= 1.12
  lang: [{otp: '24.3.4.13', elixir: '1.12.3'}, {otp: '26.0.2', elixir: '1.15.5'}, {otp: '26.2.3', elixir: '1.17.1'}]
- postgres: ['13.12', '16.0']
+ postgres: ['13.12', '14.5', 16.0']
  services:
  postgres:
  image: postgres:${{matrix.postgres}}