How to run Strapi after pulling it from GitHub(with postgres DB)?

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2

Concerning the credentials you should never push them with your code to github.
Rather use environmental variables (a .env file inside the root folder) where you store the values locally and add it to gitignore. Afterwards use the variables inside the database.js like:

module.exports = ({ env }) => ({
  connection: {
    client: 'mysql',
    connection: {
      host: env('DATABASE_HOST'),
      port: env.int('DATABASE_PORT'),
      database: env('DATABASE_NAME'),
      user: env('DATABASE_USERNAME'),
      password: env('DATABASE_PASSWORD'),
      ssl: {
        rejectUnauthorized: env.bool('DATABASE_SSL_SELF', false), // For self-signed certificates
      },
    },
    debug: false,
  },
});

Your collegues should probably receive their very own db account and put their credentials inside their .env file.