metropolis/cli/metroctl: fix %v in cases where we should use %w

Change-Id: I5504dd8d12fe09d4373df619a3cecbfa39c7587b
Reviewed-on: https://review.monogon.dev/c/monogon/+/3097
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/cli/metroctl/core/rpc.go b/metropolis/cli/metroctl/core/rpc.go
index b469544..a5aac60 100644
--- a/metropolis/cli/metroctl/core/rpc.go
+++ b/metropolis/cli/metroctl/core/rpc.go
@@ -25,7 +25,7 @@
 	if c.ProxyServer != "" {
 		socksDialer, err := proxy.SOCKS5("tcp", c.ProxyServer, nil, proxy.Direct)
 		if err != nil {
-			return nil, fmt.Errorf("failed to build a SOCKS dialer: %v", err)
+			return nil, fmt.Errorf("failed to build a SOCKS dialer: %w", err)
 		}
 		grpcd := func(_ context.Context, addr string) (net.Conn, error) {
 			return socksDialer.Dial("tcp", addr)
@@ -61,7 +61,7 @@
 	if proxyAddr != "" {
 		socksDialer, err := proxy.SOCKS5("tcp", proxyAddr, nil, proxy.Direct)
 		if err != nil {
-			return nil, fmt.Errorf("failed to build a SOCKS dialer: %v", err)
+			return nil, fmt.Errorf("failed to build a SOCKS dialer: %w", err)
 		}
 		grpcd := func(_ context.Context, addr string) (net.Conn, error) {
 			return socksDialer.Dial("tcp", addr)