Update ruby_speech requirement from ~> 2.0 to >= 2, < 4

[dependabot]

Updates the requirements on ruby_speech to permit the latest version.

Changelog

Sourced from ruby_speech's changelog.

2.4.0 - 2018-02-23

• Feature: Permit percentage rate values for prosody tags
• Bugfix: Rulerefs referenced n-levels deep under Rulerefs should be expanded.
• Bugfix: Optimize performance of built-in number DTMF grammar
• Bugfix: Fix handling of millisecond values

2.3.2 - 2014-04-21

• Bugfix: String nodes should take non-strings and cast to a string (#to_s)
• Bugfix: Cleanly handle NLSML with no input tag
• Bugfix: Drawing an NLSML doc should return something structured/parsed
• Bugfix: Cloning SSML documents no longer turns them into GRXML docs

2.3.1 - 2014-02-24

• Bugfix: Phone number grammar should only allow a single instance of '*'/'x'
• Bugfix: Concatenating documents containing strings across the border inserts appropriate spacing (#21).

2.3.0 - 2013-09-30

• Feature: Allow generation of a boolean, date, digits, currency, number, phone or time grammar including from URIs
• Bugfix: Ensure that rule refs can be reused when inlining grammars

2.2.2 - 2013-09-03

• Bugfix: Fix an exception message to include object type

2.2.1 - 2013-07-02

• Bugfix: Ensure that concatenating documents doesn't mutate the originals on JRuby

2.2.0 - 2013-06-26

• Bugfix: Constant autoload in rbx C extensions doesn't work properly
• Bugfix: No longer subclass or copy nodes, use delegation instead
• Bugfix: Java 1.6 compatability
• CS: Remove niceogiri dependency
• CS: Remove autoloading
• CS: Depend on activesupport less

2.1.2 - 2013-06-05

• Bugfix: Allow wrapping a pre-parsed XML node nested arbitrary deeply as an NLSML document

2.1.1 - 2013-05-09

• Bugfix: Support numeric SISR literal tags

2.1.0 - 2013-05-07

• Feature: Support for SISR literal syntax

2.0.2 - 2013-05-01

• Bugfix: Differentiate between GRXML match cases with are and are not maximal
  • A Match can accept further input while still matching, while a a MaxMatch cannot.
  • Matching implementation moved down to C/Java to avoid repeated regex compilation and confusing jumping about.
• Bugfix: Back to functioning on JRuby with latest Nokogiri release

2.0.1 - 2013-04-27

... (truncated)

Commits

• bb5b33b Merge branch 'release/2.4.0'
• 88c43d1 Bump to 2.4.0
• 62fa847 Merge pull request #51 from adhearsion/changelog-ms
• aff1095 Add CHANGELOG entry for milliseconds fix
• 8a577db Merge pull request #49 from adhearsion/bugfix/milliseconds
• b319b70 [BUGFIX] Fix handling of millisecond values (#48)
• 77ffd0e Merge pull request #50 from adhearsion/ci/oraclejdk7
• 45fe1df [CI] Drop jruby-head/openjdk7 environment
• 4627879 [CI] Set JRUBY_OPTS with env instead of before_script
• 970e6cd [CI] Bump JRuby version to 9.1.13.0
• Additional commits viewable in compare view

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