Merge pull request #1194 from rust-lang/dependabot/cargo/once_cell-1.6.0

Cargo.lock

@@ -1054,9 +1054,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.5.2"
+version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "13bd41f508810a131401606d54ac32a467c97172d74ba7662562ebba5ad07fa0"
+checksum = "4ad167a2f54e832b82dbe003a046280dceffe5227b5f79e08e363a29638cfddd"
 
 [[package]]
 name = "opaque-debug"