Add bcrypt_pbkdf gem.

Add the bcrypt_pbkdf gem. This is required to be able to use manually
configured SSH keys with the SFTP storage manager.

Gemfile

@@ -50,6 +50,7 @@ gem 'hsluv'
 gem 'google-cloud-bigquery', require: "google/cloud/bigquery"
 gem 'google-cloud-storage', require: "google/cloud/storage"
 gem 'ed25519'
+gem 'bcrypt_pbkdf' # https://github.com/net-ssh/net-ssh/issues/565
 gem 'terminal-table'
 
 group :production, :staging do

Gemfile.lock

@@ -106,6 +106,7 @@ GEM
     aws-sigv4 (1.2.3)
       aws-eventstream (~> 1, >= 1.0.2)
     bcrypt (3.1.16)
+    bcrypt_pbkdf (1.1.0)
     benchmark-ips (2.8.4)
     better_errors (2.9.1)
       coderay (>= 1.0.0)
@@ -476,6 +477,7 @@ DEPENDENCIES
   addressable
   aws-sdk-sqs (~> 1)
   bcrypt
+  bcrypt_pbkdf
   benchmark-ips
   better_errors
   binding_of_caller