dropbear: disable RSA-SHA1 by default

Upstream has disabled SHA-1 algorithms by default since version 2025.87.
SHA-1 has known weakness and most SSH implementations support alternatives.

Signed-off-by: Konstantin Demin <rockdrilla@gmail.com>

Author: rockdrilla

package/network/services/dropbear/Config.in

@@ -822,7 +822,6 @@ menu "Encryption options"
 
 	config DROPBEAR_RSA_SHA1
 		bool "RSA-SHA1 [WEAK]"
-		default y
 		depends on DROPBEAR_LEGACY_COMPAT
 		help
 			This enables the following public key algorithm: