build(deps): bump retain_mut from 0.1.2 to 0.1.7

Bumps [retain_mut](https://github.com/upsuper/retain_mut) from 0.1.2 to 0.1.7.
- [Release notes](https://github.com/upsuper/retain_mut/releases)
- [Commits](https://github.com/upsuper/retain_mut/commits)

---
updated-dependencies:
- dependency-name: retain_mut
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Cargo.lock

@@ -1608,9 +1608,9 @@ dependencies = [
 
 [[package]]
 name = "retain_mut"
-version = "0.1.2"
+version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "53552c6c49e1e13f1a203ef0080ab3bbef0beb570a528993e83df057a9d9bba1"
+checksum = "8c31b5c4033f8fdde8700e4657be2c497e7288f01515be52168c631e2e4d4086"
 
 [[package]]
 name = "rlimit"

src/uu/tee/Cargo.toml

@@ -17,7 +17,7 @@ path = "src/tee.rs"
 [dependencies]
 clap = { version = "3.1", features = ["wrap_help", "cargo"] }
 libc = "0.2.124"
-retain_mut = "=0.1.2" # ToDO: [2021-01-01; rivy; maint/MinSRV] ~ v0.1.5 uses const generics which aren't stabilized until rust v1.51.0
+retain_mut = "=0.1.7" # ToDO: [2021-01-01; rivy; maint/MinSRV] ~ v0.1.5 uses const generics which aren't stabilized until rust v1.51.0
 uucore = { version=">=0.0.11", package="uucore", path="../../uucore", features=["libc"] }
 
 [[bin]]