Ensure Docker versions are valid Dependabot::Versions

[Nishnha]

Fixes #7938

WIP

Dependabot::Docker::Version#new would normally return an instance of a Gem::Version with an actual value, but Docker::Version#initialize failed to call #super and so it returned Gem::Version.new(nil) instead.

This PR fixes that issue in the Dependabot::Docker::Version class by actually calling #super and it also removes the overloaded #self.correct?(version) method that was present since the base method should now work correctly.

Finally, in Updater::GroupUpdateCreation we make sure to cast the version returned by the latest version finder to an actual Dependabot::Version so we can use the Dependabot::Version#segments method.

[yeikel]

Can we add a spec that reproduces this (and proves the fix?)

[Nishnha]

I added a couple of tests in f0a27a1 and fcbb08a.

• The test in f0a27a1 takes a few string versions and converts them to a Docker::Version and then checks whether they are correct (i.e. whether they are a valid Gem::Version).

• The test in fcbb08a does the same thing but it uses version strings from a DependencySnapshot in the GroupUpdateAllVersions spec. The DependencySnapshot is for a Docker dependency with a version in the form "v2.0.20230509134123". This is the I could get to recreating the GroupUpdateCreation issue without adding a whole new test fixture.

If the test in fcbb08a isn't thorough enough I could add a new test fixture - I was able to recreated the issue in a public test repo.

I know this patch works though because I can now run the previously erroring update locally:

2023/09/08 01:55:27 INFO Raven 3.1.2 configured not to capture errors: DSN not set
2023/09/08 01:55:42 INFO Starting job processing
2023/09/08 01:55:42 INFO Starting grouped update job for dark-dependabot/docker-semver-groups
2023/09/08 01:55:42 INFO Found 1 group(s).
2023/09/08 01:55:42 INFO Starting update group for 'docker-semver-group'
2023/09/08 01:55:42 INFO Checking if kustomize/kustomize v4.5.5 needs updating
2023/09/08 01:55:43 INFO Latest version is v5.0.1
2023/09/08 01:55:43 INFO Requirements to unlock own
2023/09/08 01:55:43 INFO Requirements update strategy
2023/09/08 01:55:43 INFO Updating kustomize/kustomize from v4.5.5 to v5.0.1
2023/09/08 01:55:43 INFO Checking if alpine/helm 3.11.1 needs updating
2023/09/08 01:55:45 INFO Latest version is 3.12.3
2023/09/08 01:55:45 INFO Requirements to unlock own
2023/09/08 01:55:45 INFO Requirements update strategy
2023/09/08 01:55:45 INFO Updating alpine/helm from 3.11.1 to 3.12.3
2023/09/08 01:55:45 INFO Checking if golang 1.21.0-bullseye needs updating
2023/09/08 01:55:47 INFO Latest version is 1.21.1-bullseye
2023/09/08 01:55:47 INFO Requirements to unlock own
2023/09/08 01:55:47 INFO Requirements update strategy
2023/09/08 01:55:47 INFO Updating golang from 1.21.0-bullseye to 1.21.1-bullseye
2023/09/08 01:55:47 INFO Creating a pull request for 'docker-semver-group'
2023/09/08 01:55:48 INFO Finished job processing
2023/09/08 01:55:48 INFO Results:
+------------------------------------------------------------------------------------------------------------------------------------+
|                                                Changes to Dependabot Pull Requests                                                 |
+---------+--------------------------------------------------------------------------------------------------------------------------+
| created | kustomize/kustomize ( from v4.5.5 to v5.0.1 ), alpine/helm ( from 3.11.1 to 3.12.3 ), golang ( from 1.21.0-bullseye t... |
+---------+--------------------------------------------------------------------------------------------------------------------------+

[jurre]

This looks good to me 👍

[yeikel]

Thank you for adding the tests, and sorry for the delayed response

[Nishnha]

All good thanks for the initial review