K8SPG-757: fix version check

[pooknull]

https://perconadev.atlassian.net/browse/K8SPG-757

DESCRIPTION

Problem:
https://github.com/percona/percona-postgresql-operator/pull/1202/files PR had invalid version set inside the CompareVersionmethod .

Solution:
Set it to 2.8.0.

CHECKLIST

Jira

• Is the Jira ticket created and referenced properly?
• Does the Jira ticket have the proper statuses for documentation (Needs Doc) and QA (Needs QA)?
• Does the Jira ticket link to the proper milestone (Fix Version field)?

Tests

• Is an E2E test/test case added for the new feature/change?
• Are unit tests added where appropriate?

Config/Logging/Testability

• Are all needed new/changed options added to default YAML files?
• Are all needed new/changed options added to the Helm Chart?
• Did we add proper logging messages for operator actions?
• Did we ensure compatibility with the previous version or cluster upgrade process?
• Does the change support oldest and newest supported PG version?
• Does the change support oldest and newest supported Kubernetes version?

[JNKPercona]

Test Name	Result	Time
backup-enable-disable	passed	00:06:29
custom-extensions	passed	00:14:34
custom-tls	passed	00:05:42
database-init-sql	passed	00:05:09
demand-backup	passed	00:24:32
finalizers	passed	00:03:48
init-deploy	passed	00:02:42
monitoring	passed	00:07:47
monitoring-pmm3	failure	00:06:27
one-pod	passed	00:06:05
operator-self-healing	passed	00:08:16
pgvector-extension	passed	00:02:36
pitr	passed	00:11:20
scaling	passed	00:04:57
scheduled-backup	passed	00:29:50
self-healing	passed	00:08:26
sidecars	passed	00:02:27
start-from-backup	passed	00:12:21
tablespaces	passed	00:06:40
telemetry-transfer	passed	00:03:23
upgrade-consistency	failure	00:05:57
upgrade-minor	passed	00:05:39
users	passed	00:04:20
We run 23 out of 23		03:09:39

commit: 965600b
image: perconalab/percona-postgresql-operator:PR-1287-965600b23