Update go dependencies

vendor/github.com/dgrijalva/jwt-go/signing_method.go

@@ -1,35 +0,0 @@
-package jwt
-
-import (
-	"sync"
-)
-
-var signingMethods = map[string]func() SigningMethod{}
-var signingMethodLock = new(sync.RWMutex)
-
-// Implement SigningMethod to add new methods for signing or verifying tokens.
-type SigningMethod interface {
-	Verify(signingString, signature string, key interface{}) error // Returns nil if signature is valid
-	Sign(signingString string, key interface{}) (string, error)    // Returns encoded signature or error
-	Alg() string                                                   // returns the alg identifier for this method (example: 'HS256')
-}
-
-// Register the "alg" name and a factory function for signing method.
-// This is typically done during init() in the method's implementation
-func RegisterSigningMethod(alg string, f func() SigningMethod) {
-	signingMethodLock.Lock()
-	defer signingMethodLock.Unlock()
-
-	signingMethods[alg] = f
-}
-
-// Get a signing method from an "alg" string
-func GetSigningMethod(alg string) (method SigningMethod) {
-	signingMethodLock.RLock()
-	defer signingMethodLock.RUnlock()
-
-	if methodF, ok := signingMethods[alg]; ok {
-		method = methodF()
-	}
-	return
-}