chore: Upgrade packages to support and netcore3.1 (#4)

* chore: Upgrade to netstandard 2.1 and netcore3.1

* chore: remove ide files

* chore: add ide files to gitignore

* chore: downgrade to netstandard2.0

(+semver: patch) upgrade prometheus-net to 3.1.2 (#2)

Signed-off-by: Joshua Benjamin <[email protected]>

(+semver: fix) Fixed typo in "system" label

(+semver: fix) Fixed typo in "system" label

(+semver: major) Prometheus-ified the monitoring implementation

Now creates labels on metrics and ignores Akka.Monitoring's rollup behavior. (i.e., only metrics that have been passed through CounterNames.ActorSpecificCategory() will be collected.)

(+semver: fix) Fixed it again.

(+semver: fix) Fixed it again.

(+semver: major) Initial implementation