Bump prometheus_exporter from 0.8.1 to 1.0.0

Bumps [prometheus_exporter](https://github.com/discourse/prometheus_exporter) from 0.8.1 to 1.0.0.
- [Release notes](https://github.com/discourse/prometheus_exporter/releases)
- [Changelog](https://github.com/discourse/prometheus_exporter/blob/master/CHANGELOG)
- [Commits](https://github.com/discourse/prometheus_exporter/compare/v0.8.1...v1.0.0)

---
updated-dependencies:
- dependency-name: prometheus_exporter
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Gemfile.lock

@@ -304,7 +304,7 @@ GEM
       ast (~> 2.4.1)
     path_expander (1.1.0)
     pg (1.2.3)
-    prometheus_exporter (0.8.1)
+    prometheus_exporter (1.0.0)
       webrick
     pry (0.13.1)
       coderay (~> 1.1)