Bump google.golang.org/grpc from 1.59.0 to 1.60.1

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.59.0 to 1.60.1.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.59.0...v1.60.1)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/google.golang.org/grpc/internal/transport/proxy.go

@@ -28,6 +28,8 @@ import (
 	"net/http"
 	"net/http/httputil"
 	"net/url"
+
+	"google.golang.org/grpc/internal"
 )
 
 const proxyAuthHeaderKey = "Proxy-Authorization"
@@ -112,7 +114,7 @@ func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, backendAddr stri
 // proxyDial dials, connecting to a proxy first if necessary. Checks if a proxy
 // is necessary, dials, does the HTTP CONNECT handshake, and returns the
 // connection.
-func proxyDial(ctx context.Context, addr string, grpcUA string) (conn net.Conn, err error) {
+func proxyDial(ctx context.Context, addr string, grpcUA string) (net.Conn, error) {
 	newAddr := addr
 	proxyURL, err := mapAddress(addr)
 	if err != nil {
@@ -122,15 +124,15 @@ func proxyDial(ctx context.Context, addr string, grpcUA string) (conn net.Conn,
 		newAddr = proxyURL.Host
 	}
 
-	conn, err = (&net.Dialer{}).DialContext(ctx, "tcp", newAddr)
+	conn, err := internal.NetDialerWithTCPKeepalive().DialContext(ctx, "tcp", newAddr)
 	if err != nil {
-		return
+		return nil, err
 	}
-	if proxyURL != nil {
+	if proxyURL == nil {
 		// proxy is disabled if proxyURL is nil.
-		conn, err = doHTTPConnectHandshake(ctx, conn, addr, proxyURL, grpcUA)
+		return conn, err
 	}
-	return
+	return doHTTPConnectHandshake(ctx, conn, addr, proxyURL, grpcUA)
 }
 
 func sendHTTPRequest(ctx context.Context, req *http.Request, conn net.Conn) error {