Change mention of 2.7.3 to 2.7.5 in Nomad (#8934)

**What this PR does / why we need it**:

Missed this in the previous PR.

**Checklist**
- [X] Reviewed the
[`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md)
guide (**required**)
- [ ] Documentation added
- [ ] Tests updated
- [ ] `CHANGELOG.md` updated
- [ ] Changes that require user attention or interaction to upgrade are
documented in `docs/sources/upgrading/_index.md`

Signed-off-by: Michel Hollands <michel.hollands@grafana.com>

production/nomad/loki/README.md

@@ -22,7 +22,7 @@ To deploy a different version change `variable.version` default value or
 specify from command line:
 
 ```shell
-nomad job run -var="version=2.7.3" job.nomad.hcl
+nomad job run -var="version=2.7.5" job.nomad.hcl
 ```
 
 ### Scale Loki