Update cosign generate cmd to not include newline

Removing the newline will result in a payload and sha256sum that is
equivalent to what you get with the --output-payload flag and inside
the hashedrekordobj.data.hash.value field.

Signed-off-by: Lily Sturmann <lsturman@redhat.com>

cmd/cosign/cli/generate/generate.go

@@ -49,6 +49,6 @@ func GenerateCmd(ctx context.Context, regOpts options.RegistryOptions, imageRef
 	if err != nil {
 		return err
 	}
-	fmt.Fprintln(w, string(json))
+	fmt.Fprint(w, string(json))
 	return nil
 }

internal/pkg/cosign/rekor/signer.go

@@ -56,12 +56,12 @@ var _ cosign.Signer = (*signerWrapper)(nil)
 
 // Sign implements `cosign.Signer`
 func (rs *signerWrapper) Sign(ctx context.Context, payload io.Reader) (oci.Signature, crypto.PublicKey, error) {
-	sig, pub, err := rs.inner.Sign(ctx, payload)
+	sig, pub, err := rs.inner.Sign(ctx, payload) // type "github.com/sigstore/cosign/v2/internal/pkg/cosign".Signer
 	if err != nil {
 		return nil, nil, err
 	}
 
-	payloadBytes, err := sig.Payload()
+	payloadBytes, err := sig.Payload() // sig type: oci.Signature
 	if err != nil {
 		return nil, nil, err
 	}