Fix multiple backwards compatibility issues found in fpm v1.17.0

[jordansissel]

Fixes:

• Avoid endless range, use -1 as end of range if appropriate. (introduced in ruby 2.6.0)
• Avoid using String arg for StringScanner#scan(), use regex instead. (was introduced in ruby 2.7.0)
• Avoid Array#filter, use Array#select instead (was introduced in ruby 2.6.0)

Fixes #2120

[jordansissel]

GHA test suite doesn't test Ruby 2.7, so I'm testing locally ---

on ruby 2.5.0, the full test suite result:

Finished in 1 minute 5.48 seconds (files took 0.58767 seconds to load)
384 examples, 1 failure, 9 pending

The one failure seems to be a bug or misuse of fileutils:

Failures:

  1) FPM::Util#copy_entry when given files that are symlinks should keep those files as symlinks
     Failure/Error:
       FileUtils.copy_entry(src, dst, preserve, false,
                            remove_destination)

     Errno::EOPNOTSUPP:
       Operation not supported @ apply2files - /tmp/studtmp-be49cbef4f17864f8df405f8092185960f1584380b887eb72f577c6c2536/b
     # ./lib/fpm/util.rb:376:in `copy_entry'
     # ./spec/fpm/util_spec.rb:28:in `block (6 levels) in <top (required)>'
     # ./spec/fpm/util_spec.rb:24:in `block (5 levels) in <top (required)>'
     # ./spec/fpm/util_spec.rb:18:in `block (4 levels) in <top (required)>'

On ruby 2.5.0 and Linux, calling FileUtils#copy_entry with preserve=true will fail because lchmod is not implemented, it looks like?

Testing in isolation:

% ls -ld /tmp/b
lrwxrwxrwx. 1 jls jls 6 Nov 13 23:33 /tmp/b -> /tmp/a
% ruby -rfileutils -e 'FileUtils.copy_entry("/tmp/b", "/tmp/c", true, false, true)'
Traceback (most recent call last):
        5: from -e:1:in `<main>'
        4: from /home/jls/.rbenv/versions/2.5.0/lib/ruby/2.5.0/fileutils.rb:415:in `copy_entry'
        3: from /home/jls/.rbenv/versions/2.5.0/lib/ruby/2.5.0/fileutils.rb:1396:in `wrap_traverse'
        2: from /home/jls/.rbenv/versions/2.5.0/lib/ruby/2.5.0/fileutils.rb:421:in `block in copy_entry'
        1: from /home/jls/.rbenv/versions/2.5.0/lib/ruby/2.5.0/fileutils.rb:1319:in `copy_metadata'
/home/jls/.rbenv/versions/2.5.0/lib/ruby/2.5.0/fileutils.rb:1319:in `lchmod': Operation not supported @ apply2files - /tmp/c (Errno::EOPNOTSUPP)

Same error, basically. This failure seems unrelated to this change and more about how fpm may be calling copy_entry incorrectly for symlinks? I'll ignroe it for this issue.

[jordansissel]

Found it -- I"ll fix it here anyway. The test suite is calling FileUtil#copy_entry with preserve=true for a symlink and this errors on Ruby 2.5.0, but not 3.4.0.

[jordansissel]

New test, 2.5.0: 384 examples, 0 failures, 9 pending

Passes on 3.4.0 also