Update mongodb_exporter from 0.40.0 to 0.42.1

[prometheus-rpm-bot]

https://github.com/percona/mongodb_exporter/releases/tag/v0.42.1
Release notes:

## What's Changed
* PMM-13477 Support MongoDB 8.0 by @BupycHuk in https://github.com/percona/mongodb_exporter/pull/943
* PMM-13519: Drop Mongo URI from logs by @idoqo in https://github.com/percona/mongodb_exporter/pull/952
* PMM-12219 support special characters in password. by @BupycHuk in https://github.com/percona/mongodb_exporter/pull/949
* PMM-7 use image from ENV for standalone encrypted by @BupycHuk in https://github.com/percona/mongodb_exporter/pull/695
* Add shard label in collstats metrics by @steveteuber in https://github.com/percona/mongodb_exporter/pull/942
* replSetGetConfigCollector by @hiroshi in https://github.com/percona/mongodb_exporter/pull/295
* Add code coverage action in pipeline by @ShashankSinha252 in https://github.com/percona/mongodb_exporter/pull/569

## Dependency Updates
* Bump github.com/prometheus/common from 0.60.0 to 0.60.1 by @dependabot in https://github.com/percona/mongodb_exporter/pull/941
* Bump github.com/alecthomas/kong from 1.2.1 to 1.3.0 by @dependabot in https://github.com/percona/mongodb_exporter/pull/944
* Bump github.com/prometheus/exporter-toolkit from 0.13.0 to 0.13.1 by @dependabot in https://github.com/percona/mongodb_exporter/pull/945
* Bump github.com/alecthomas/kong from 1.3.0 to 1.4.0 by @dependabot in https://github.com/percona/mongodb_exporter/pull/956
* Bump github.com/golangci/golangci-lint from 1.61.0 to 1.62.0 in /tools by @dependabot in https://github.com/percona/mongodb_exporter/pull/957

## New Contributors
* @steveteuber made their first contribution in https://github.com/percona/mongodb_exporter/pull/942

**Full Changelog**: https://github.com/percona/mongodb_exporter/compare/v0.42.0...v0.42.1