Release v5.20.0

- docker/referece: add IsFullIdentifier
- Changed oci layout transport to thread-safe destination
- add pkg/blobcache from Buildah
- blobcache: drop import on buildah/docker
- blobcache: drop history comment
- blobcache: make `ClearCache()` private
- blobcache: remove `CacheLookupReferenceFunc`
- blobcache: turn BlobCache into a struct
- blobcache: export clearCache
- Remove (unused and unreachable) keyring support
- Eliminate a goroutine
- Also introduces internal-only interfaces to allow extending the
  transport feature set in the future

Signed-off-by: Miloslav Trmač <[email protected]>

version/version.go

@@ -6,12 +6,12 @@ const (
 	// VersionMajor is for an API incompatible changes
 	VersionMajor = 5
 	// VersionMinor is for functionality in a backwards-compatible manner
-	VersionMinor = 19
+	VersionMinor = 20
 	// VersionPatch is for backwards-compatible bug fixes
-	VersionPatch = 2
+	VersionPatch = 0
 
 	// VersionDev indicates development branch. Releases will be empty string.
-	VersionDev = "-dev"
+	VersionDev = ""
 )
 
 // Version is the specification version that the package types support.