[Presence] Change new unused signature_version field to string type for easier debugging and to align with [nearby_resources.proto](https://source.corp.google.com/piper///depot/google3/google/internal/location/nearby/presence/v1/nearby_resources.proto;l=96)

PiperOrigin-RevId: 615921095

internal/proto/credential.proto

@@ -43,7 +43,7 @@ enum CredentialType {
 // The shared credential is derived from local credential, and distributed to
 // remote devices based on the trust token for identity decryption and
 // authentication.
-// NEXT_ID=17
+// NEXT_ID=18
 // LINT.IfChange(SharedCredential)
 message SharedCredential {
   // The randomly generated unique id of the public credential.
@@ -104,6 +104,6 @@ message SharedCredential {
 
   // Signature algorithm version. Used to determine which algorithm to use to
   // verify incoming signatures.
-  bytes signature_version = 16;
+  string signature_version = 16;
 }
 // LINT.ThenChange(//depot/google3/google/internal/location/nearby/presence/v1/nearby_resources.proto:SharedCredential)

internal/proto/local_credential.proto

@@ -28,7 +28,7 @@ option optimize_for = LITE_RUNTIME;
 // The local credential contains information of a local device for
 // identity encryption and authentication. It should never leave the generating
 // device.
-// NEXT_ID=11
+// NEXT_ID=13
 message LocalCredential {
   // Private signing key descriptor.
   // For Ed25519PrivateKey, both `certificate_alias` and `encrypted_key` is set.
@@ -81,5 +81,5 @@ message LocalCredential {
 
   // Signature algorithm version. Used to determine which algorithm to use to
   // sign data.
-  bytes signature_version = 12;
+  string signature_version = 12;
 }