Update mockito requirement from 0.30.0 to 0.31.0 in /crates/volta-core

Updates the requirements on [mockito](https://github.com/lipanski/mockito) to permit the latest version.
- [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
...

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

Author: dependabot[bot]

crates/volta-core/Cargo.toml

@@ -31,7 +31,7 @@ tempfile = "3.3.0"
 os_info = "3.2.0"
 detect-indent = { git = "https://github.com/stefanpenner/detect-indent-rs", branch = "master" }
 envoy = "0.1.3"
-mockito = { version = "0.30.0", optional = true }
+mockito = { version = "0.31.0", optional = true }
 regex = "1.5.4"
 dirs = "4.0.0"
 sha-1 = "0.10.0"