[DRE-maint] ruby-train is marked for autoremoval from testing

[Debian testing autoremoval watch]

ruby-train 3.2.20-2 is marked for autoremoval from testing on 2020-04-11

It (build-)depends on packages with these RC bugs:
952045: ruby-net-scp: FTBFS: ERROR: Test "ruby2.7" failed: Error: test_upload_file_with_metacharacters_in_name_should_escape_remote_file_name(TestUpload): RuntimeError: expected string "scp -t /path/to/remote/\\\u0001\\\u0002\\\u0003\\\u0004\\\u0005\\\u0006\\\a\\\b\\\t\\\v\\\f\\\r\\\u000E\\\u000F\\\u0010\\\u0011\\\u0012\\\u0013\\\u0014\\\u0015\\\u0016\\\u0017\\\u0018\\\u0019\\\u001A\\\e\\\u001C\\\u001D\\\u001E\\\u001F\\ \\!\\\"\\#\\$\\%\\&\\'\\(\\)\\*\\+,-.0123456789:\\;\\<\\=\\>\\?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\[\\\\\\]\\^_\\`abcdefghijklmnopqrstuvwxyz\\{\\|\\}\\~\\\u007F.txt" but got "scp -t /path/to/remote/\\\x01\\\x02\\\x03\\\x04\\\x05\\\x06\\\a\\\b\\\t\\\v\\\f\\\r\\\x0E\\\x0F\\\x10\\\x11\\\x12\\\x13\\\x14\\\x15\\\x16\\\x17\\\x18\\\x19\\\x1A\\\e\\\x1C\\\x1D\\\x1E\\\x1F\\ \\!\\\"\\#\\$\\%\\&\\'\\(\\)\\*+,-.0123456789:\\;\\<\\=\\>\\?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\[\\\\\\]\\^_\\`abcdefghijklmnopqrstuvwxyz\\{\\|\\}\\~\\\x7F.txt"