fix(que): handle change in capitalisation of framework version constant for Que in v1.x

[tomlongridge]

Goal

As per @tommieer's fix in #570 but preserving backwards compatibility.

The ::Que::Version constant was capitalised in the beta 1.x branch and so this breaks reporting for this Que release.

Changeset

Changed

• que.rb - conditionally tested for existence of version constants

Tests

• Manually tested on v0.14.3 and v1.0.0-beta3
• No changes to tests as the original spec still stands for the non-beta release.

Linked issues

Related to #570

Review

For the submitter, initial self-review:

• Commented on code changes inline explain the reasoning behind the approach
• Reviewed the test cases added for completeness and possible points for discussion
• A changelog entry was added for the goal of this pull request
• Check the scope of the changeset - is everything in the diff required for the pull request?
• This pull request is ready for:
  • Initial review of the intended approach, not yet feature complete
  • Structural review of the classes, functions, and properties modified
  • Final review

For the pull request reviewer(s), this changeset has been reviewed for:

• Consistency across platforms for structures or concepts added or modified
• Consistency between the changeset and the goal stated above
• Internal consistency with the rest of the library - is there any overlap between existing interfaces and any which have been added?
• Usage friction - is the proposed change in usage cumbersome or complicated?
• Performance and complexity - are there any cases of unexpected O(n^3) when iterating, recursing, flat mapping, etc?
• Concurrency concerns - if components are accessed asynchronously, what issues will arise
• Thoroughness of added tests and any missing edge cases
• Idiomatic use of the language