Bump ring from 0.16.15 to 0.16.18 (#192)

Bumps [ring](https://github.com/briansmith/ring) from 0.16.15 to 0.16.18.
- [Release notes](https://github.com/briansmith/ring/releases)
- [Commits](https://github.com/briansmith/ring/commits)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Cargo.lock

@@ -90,9 +90,9 @@ checksum = "08c48aae112d48ed9f069b33538ea9e3e90aa263cfa3d1c24309612b1f7472de"
 
 [[package]]
 name = "cc"
-version = "1.0.61"
+version = "1.0.65"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed67cbde08356238e75fc4656be4749481eeffb09e19f320a25237d5221c985d"
+checksum = "95752358c8f7552394baf48cd82695b345628ad3f170d607de3ca03b8dacca15"
 
 [[package]]
 name = "cfg-if"
@@ -472,9 +472,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.4.1"
+version = "1.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "260e51e7efe62b592207e9e13a68e43692a7a279171d6ba57abd208bf23645ad"
+checksum = "13bd41f508810a131401606d54ac32a467c97172d74ba7662562ebba5ad07fa0"
 
 [[package]]
 name = "opaque-debug"
@@ -648,9 +648,9 @@ checksum = "8cab7a364d15cde1e505267766a2d3c4e22a843e1a601f0fa7564c0f82ced11c"
 
 [[package]]
 name = "ring"
-version = "0.16.15"
+version = "0.16.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "952cd6b98c85bbc30efa1ba5783b8abf12fec8b3287ffa52605b9432313e34e4"
+checksum = "70017ed5c555d79ee3538fc63ca09c70ad8f317dcadc1adc2c496b60c22bb24f"
 dependencies = [
  "cc",
  "libc",