feat(db-manager): add POSTGRES_ALLOW_SELF_SIGNED_CERTIFICATES env variable

src/dbManager/connectionConfig.js

 const config = require('config')
 
+const { isEnvVariableTrue } = require('../utils/env')
+
 const connection =
   process.env.DATABASE_URL ||
   (config['pubsweet-server'] && config['pubsweet-server'].db)
 
+if (isEnvVariableTrue(process.env.POSTGRES_ALLOW_SELF_SIGNED_CERTIFICATES)) {
+  if (!connection.ssl) connection.ssl = {}
+  connection.ssl.rejectUnauthorized = false
+}
+
 module.exports = connection

src/utils/env.js

+const isEnvVariableTrue = variable => {
+  return variable === '1' || variable === 1 || variable === 'true'
+}
+
+module.exports = {
+  isEnvVariableTrue,
+}