Additionally consider PR merge commits when filtering PRs

[wagoodman]

This PR adds the ability for chronicle to consider PR merge commits relative to the release branch as a primary source of evidence for what to include or exclude from a release.

Take for example the following state:

• PR 45 has been merged at 2023-01-17 19:27:24 UTC (relative to GitHub servers), but the tag was done locally at 2023-01-17 19:27:23 UTC. Note, they are 1 second off, implying that there is drift from the local time and GitHub's servers.
• Result: PR 45 gets excluded from the last release (v0.2.0) and included in the next release.
• Expected result: PR 45 should be in the v0.2.0 release and not the next release.

This PR takes PR merge commits into consideration:

[0000] DEBUG github summarizer owner=wagoodman repo=test-repo
[0000]  INFO until the current revision
[0000]  INFO since release-timestamp=2023-01-17 19:32:19 UTC tag=v0.2.0
[0000] TRACE searching commit range since=66b2b06b9a2eb9647acf55e8536c4d49e5d66066 until=1af3e39dedeb5d9c7d1a2a1a5bcc946fcb5a3fb0
[0000] DEBUG release comprised of 3 commits
[0000] TRACE   ├── 1af3e39dedeb5d9c7d1a2a1a5bcc946fcb5a3fb0
[0000] TRACE   ├── a6a00a1ab3bfa5ea3d0890d0b6782aede1064438
[0000] TRACE   └── 4a1156459c4e2c0ec2273588012f36b7bac0d6ff
[0001] DEBUG total merged PRs discovered: 36
[0001] TRACE filtering PRs by chronology
[0001] TRACE PR #1 filtered out: merged before 2023-01-17 19:27:23 UTC (merged 2022-12-09 16:31:35 UTC)
[0001] TRACE PR #2 filtered out: merged before 2023-01-17 19:27:23 UTC (merged 2022-12-06 22:18:15 UTC)
...
[0001] TRACE PR #43 filtered out: merged before 2023-01-17 19:27:23 UTC (merged 2023-01-17 18:15:15 UTC)
[0001] TRACE PR #44 filtered out: merged before 2023-01-17 19:27:23 UTC (merged 2023-01-17 16:58:30 UTC)
[0001] TRACE PR #45 filtered out: has merge commit outside of valid set 66b2b06b9a2eb9647acf55e8536c4d49e5d66066
[0001] TRACE considering re-inclusion of PRs based on merge commits
[0001] TRACE filtering remaining PRs by qualitative traits
[0001] TRACE PR #49 filtered out: missing required label
[0001] DEBUG PRs contributing to changelog: 2
[0001] TRACE   ├── #46: merged 2023-01-18 14:23:58 UTC
[0001] TRACE   └── #47: merged 2023-01-19 18:06:28 UTC
[0001] DEBUG total closed issues discovered: 5
[0001] TRACE issue #3 filtered out: closed before 2023-01-17 19:27:23 UTC (closed 2023-01-04 18:00:28 UTC)
[0001] TRACE issue #9 filtered out: closed before 2023-01-17 19:27:23 UTC (closed 2023-01-04 17:18:25 UTC)
[0001] TRACE issue #11 filtered out: closed before 2023-01-17 19:27:23 UTC (closed 2023-01-04 17:18:24 UTC)
[0001] TRACE issue #25 filtered out: closed before 2023-01-17 19:27:23 UTC (closed 2023-01-04 16:31:22 UTC)
[0001] DEBUG issues contributing to changelog: 1
[0001] TRACE   └── #48: closed 2023-01-20 14:08:14 UTC
[0001]  INFO discovered changes: 3
[0001] DEBUG   ├── added-feature (minor bump): 1
[0001] DEBUG   └── bug-fix (patch bump): 2

Note the [0001] TRACE PR #45 filtered out: has merge commit outside of valid set 66b2b06b9a2eb9647acf55e8536c4d49e5d66066, upon attempting to release v0.3.0.

This PR additionally fully implements the anchore/go-logger interface.