Added semantic version constraints to the dependencies.

Open-ended versions for dependencies **will** inevitably break reproducible
builds.

Also removed the stale integration with <https://travis.ci>. Travis is now a
commercial offering, and the last successful build was in ~2018. Instead, the
Github workflows are now being used.

Author: evolve75

Gemfile.lock

@@ -2,25 +2,25 @@ PATH
   remote: .
   specs:
     rubytree (2.0.0.pre)
-      json (> 2.3.1)
+      json (~> 2.0, > 2.3.1)
 
 GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.2)
     diff-lcs (1.5.0)
     json (2.6.2)
-    parallel (1.21.0)
-    parser (3.0.3.2)
+    parallel (1.22.1)
+    parser (3.1.2.0)
       ast (~> 2.4.1)
     power_assert (2.0.1)
     psych (4.0.4)
       stringio
-    rainbow (3.0.0)
+    rainbow (3.1.1)
     rake (13.0.6)
     rdoc (6.4.0)
       psych (>= 4.0.0)
-    regexp_parser (2.2.0)
+    regexp_parser (2.5.0)
     rexml (3.2.5)
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
@@ -38,17 +38,17 @@ GEM
     rtags (0.97)
     rtagstask (0.0.4)
       rtags (> 0.0.0)
-    rubocop (1.24.0)
+    rubocop (1.30.1)
       parallel (~> 1.10)
-      parser (>= 3.0.0.0)
+      parser (>= 3.1.0.0)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 1.8, < 3.0)
-      rexml
-      rubocop-ast (>= 1.15.0, < 2.0)
+      rexml (>= 3.2.5, < 4.0)
+      rubocop-ast (>= 1.18.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 1.4.0, < 3.0)
-    rubocop-ast (1.15.1)
-      parser (>= 3.0.1.1)
+    rubocop-ast (1.18.0)
+      parser (>= 3.1.1.0)
     rubocop-rake (0.6.0)
       rubocop (~> 1.0)
     rubocop-rspec (2.11.1)
@@ -67,16 +67,16 @@ PLATFORMS
 
 DEPENDENCIES
   bundler
-  rake
-  rdoc
-  rspec
-  rtagstask
-  rubocop
-  rubocop-rake
-  rubocop-rspec
+  rake (~> 13.0)
+  rdoc (~> 6.0)
+  rspec (~> 3.0, > 3.10)
+  rtagstask (~> 0.0.4)
+  rubocop (~> 1.0)
+  rubocop-rake (~> 0.0)
+  rubocop-rspec (~> 2.0)
   rubytree!
-  test-unit
-  yard
+  test-unit (~> 3.0)
+  yard (~> 0.0, > 0.9)
 
 BUNDLED WITH
    2.3.4

README.md

@@ -1,7 +1,6 @@
 # **RubyTree** #
 
 [![Gem Version](https://badge.fury.io/rb/rubytree.png)](http://badge.fury.io/rb/rubytree)
-[![Travis Build Status](https://secure.travis-ci.org/evolve75/RubyTree.png)](http://travis-ci.org/evolve75/rubytree)
 [![Code Climate](https://codeclimate.com/github/evolve75/RubyTree.png)](https://codeclimate.com/github/evolve75/RubyTree)
 [![Coverage Status](https://coveralls.io/repos/evolve75/RubyTree/badge.png)](https://coveralls.io/r/evolve75/RubyTree)
 
@@ -174,11 +173,11 @@ The git repository is available at [github.com/evolve75/RubyTree][rt@github].
 
 For cloning the git repository, use one of the following commands:
 
-    $ git clone git://github.com/evolve75/RubyTree.git
+    $ git clone git://github.com/evolve75/RubyTree.git    # using ssh
 
 or
 
-    $ git clone http://github.com/evolve75/RubyTree.git
+    $ git clone https://github.com/evolve75/RubyTree.git  # using https
 
 ### Setting up the Development Environment ###
 

rubytree.gemspec

@@ -71,19 +71,19 @@ Gem::Specification.new do |s|
                             '--main', 'README.md',
                             '--quiet']
 
-  s.add_runtime_dependency 'json', '> 2.3.1'
+  s.add_runtime_dependency 'json', '~> 2.0', '> 2.3.1'
 
   # NOTE: Rake is added as a development and test dependency in the Gemfile.
   s.add_development_dependency 'bundler'
-  s.add_development_dependency 'rake'
-  s.add_development_dependency 'rdoc'
-  s.add_development_dependency 'rspec'
-  s.add_development_dependency 'rtagstask'
-  s.add_development_dependency 'rubocop'
-  s.add_development_dependency 'rubocop-rake'
-  s.add_development_dependency 'rubocop-rspec'
-  s.add_development_dependency 'test-unit'
-  s.add_development_dependency 'yard'
+  s.add_development_dependency 'rake', '~> 13.0'
+  s.add_development_dependency 'rdoc', '~> 6.0'
+  s.add_development_dependency 'rspec', '~> 3.0', '> 3.10'
+  s.add_development_dependency 'rtagstask', '~> 0.0.4'
+  s.add_development_dependency 'rubocop', '~> 1.0'
+  s.add_development_dependency 'rubocop-rake', '~> 0.0'
+  s.add_development_dependency 'rubocop-rspec', '~> 2.0'
+  s.add_development_dependency 'test-unit', '~> 3.0'
+  s.add_development_dependency 'yard', '~> 0.0', '> 0.9'
 
   s.post_install_message = <<-END_MESSAGE
     ========================================================================