Prepare release v0.18.1 (#1202)

* [BUGFIX] Fix swapped `flushedLsn` and `receiveStartTli` for `wal_receiver` collector by @spantaleev in #1198
* [BUGFIX] Fix superfluous semicolon breaking query in `process_idle` by @sysadmind in #1197 and #1201

Signed-off-by: Cristian Greco <cristian@regolo.cc>

Prepare release `0.18.0` (#1196)

* Prepare release `0.18.0`

* [FEATURE] Add `stat_progress_vacuum` collector by @ianbibby
* [FEATURE] Add `buffercache_summary` collector by @sfc-gh-pnuttall
* [FEATURE] `stat_statements`: export query itself together with `queryId` by @Delorien84
* [ENHANCEMENT] Update Go version by @SuperQ
* [ENHANCEMENT] Improve error handling for `Server.Scrape` by @BoweFlex
* [ENHANCEMENT] `stat_user_tables`: record table-only size bytes in addition to the total size bytes by @Sticksman
* [ENHANCEMENT] (chore) Fix a typo and use `slices.Contains` by @cristiangreco
* [ENHANCEMENT] Update mixin to latest changes from `grafana/postgres_exporter` by @cristiangreco, @gaantunes, @v-zhuravlev and @mshahzeb
* [ENHANCEMENT] Exclude the metrics fetching session's data from pg_stat_activity by @kmoppel
* [BUGFIX] Ensure database connections are always closed by @cristiangreco and @dehaansa

Signed-off-by: Cristian Greco <cristian@regolo.cc>

* rm entry about go update

Co-authored-by: Joe Adams <github@joeadams.io>
Signed-off-by: Cristian Greco <cristian@regolo.cc>

* add PRs

Signed-off-by: Cristian Greco <cristian@regolo.cc>

* update date

Signed-off-by: Cristian Greco <cristian@regolo.cc>

---------

Signed-off-by: Cristian Greco <cristian@regolo.cc>
Co-authored-by: Joe Adams <github@joeadams.io>