How to export version history from Serena Dimensions to Git?

I have a repository in Serena Dimensions; I need to migrate it to Github. I have figured it out that I need to use git-fast-import, but the issue I am facing is with the metadata of Serena Dimensions repo. How to export the metadata from Serena dimensions?

Note: I have updated the answer below, please upvote if you find it useful.

Here's the ruby Script

#!/usr/bin/env ruby

$stdout.binmode
$author = ""
$date = ""

require 'spreadsheet'
book = Spreadsheet.open('Metadata.xls')
sheet1 = book.worksheet('Sheet1') # can use an index or worksheet name
sheet1.each 1 do |row|
break if row[2].nil? # if first cell empty
    $author = row[2] + " <email@domain.com>"
break if row[5].nil?
    $date = row[5]
#puts row.join(',') # looks like it calls "to_s" on each cell's Value
end

$marks = []
def convert_dir_to_mark(dir)
if !$marks.include?(dir)
    $marks << dir
end
($marks.index(dir)+1).to_s
end


def convert_dir_to_date(dir)
if dir == 'current'
    return Time.now().to_i
else
    dir = dir.gsub('back_', '')
    (year, month, day) = dir.split('_')
    return Time.local(year, month, day).to_i
end
end

def export_data(string)
print "data #{string.size}\n#{string}"
end

def inline_data(file, code='M', mode='644')
content = File.read(file)
puts "#{code} #{mode} inline #{file}"
export_data(content)
end

def print_export(dir, last_mark)
date = convert_dir_to_date(dir)
mark = convert_dir_to_mark(dir)

puts 'commit refs/heads/master'
puts "mark :#{mark}"
puts "committer #{ $author } #{ date } -0700"
export_data("imported from #{dir}")
puts "from :#{last_mark}" if last_mark

puts 'deleteall'
Dir.glob("**/*").each do |file|
    next if !File.file?(file)
    inline_data(file)
end
mark
end


# Loop through the directories
last_mark = nil
Dir.chdir(ARGV[0]) do
Dir.glob("*").each do |dir|
    next if File.file?(dir)

    # move into the target directory
    Dir.chdir(dir) do
        last_mark = print_export(dir, last_mark)
    end
end
end

I exported my Dimensions metadata into a spreadsheet named 'Metadata.xls'. Then read the data from it and imported into Git by running the script.