Bump mockito from 0.30.0 to 0.31.0

Bumps [mockito](https://github.com/lipanski/mockito) from 0.30.0 to 0.31.0.
- [Release notes](https://github.com/lipanski/mockito/releases)
- [Commits](lipanski/mockito@0.30.0...0.31.0)

---
updated-dependencies:
- dependency-name: mockito
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Cargo.lock

@@ -30,7 +30,7 @@ log = { version = "0.4", features = ["std"] }
 semver = { git = "https://github.com/mikrostew/semver", branch = "new-parser" }
 structopt = "0.2.14"
 cfg-if = "1.0"
-mockito = { version = "0.30.0", optional = true }
+mockito = { version = "0.31.0", optional = true }
 test-support = { path = "crates/test-support" }
 textwrap = "0.14.2"
 which = "4.2.4"