Set default ssh.minimum_key_sizes (#9466)

The minimum key size defaults weren't set as suggested in app.ini.sample
so if you enabled MINIMUM_KEY_SIZE_CHECK it would always fail since
there would be no matching values to check against. This pr adds the
default values that should have been there.

Should fix #9465

modules/setting/setting.go

@@ -130,6 +130,7 @@ var (
 		ServerKeyExchanges: []string{"diffie-hellman-group1-sha1", "diffie-hellman-group14-sha1", "ecdh-sha2-nistp256", "ecdh-sha2-nistp384", "ecdh-sha2-nistp521", "curve25519-sha256@libssh.org"},
 		ServerMACs:         []string{"hmac-sha2-256-etm@openssh.com", "hmac-sha2-256", "hmac-sha1", "hmac-sha1-96"},
 		KeygenPath:         "ssh-keygen",
+		MinimumKeySizes:    map[string]int{"ed25519": 256, "ecdsa": 256, "rsa": 2048, "dsa": 1024},
 	}
 
 	LFS struct {
@@ -690,7 +691,6 @@ func NewContext() {
 	}
 
 	SSH.MinimumKeySizeCheck = sec.Key("MINIMUM_KEY_SIZE_CHECK").MustBool()
-	SSH.MinimumKeySizes = map[string]int{}
 	minimumKeySizes := Cfg.Section("ssh.minimum_key_sizes").Keys()
 	for _, key := range minimumKeySizes {
 		if key.MustInt() != -1 {