Consider depending on Swift Metrics 2.x (whilst still allowing 1.x)

[weissi]

Swift Metrics 2.0 just got released. It is almost completely compatible with Swift Metrics 1.x unless you exhaustively switch on the TimeUnit enum. I would highly recommend depending on swift-metrics like the following:

// swift-metrics 1.x and 2.x are almost API compatible, so most clients should use
.package(url: "https://github.com/apple/swift-metrics.git", "1.0.0" ..< "3.0.0"),

alternatively, from: "2.0.0" will also work but may in the interim cause compatibility issues with packages that specify from: "1.0.0".

If at all possible, this should be done before tagging the next release here. If using "1.0.0" ..< "3.0.0" this isn't even a SemVer major change because 1.x versions are still accepted.

[tachyonics]

Part of PR #45

[tachyonics]

Merged into master.