Use Openvpn 2.4 only

internal/provider/slickvpn/openvpnconf.go

@@ -31,11 +31,5 @@ func (p *Provider) OpenVPNConfig(connection models.Connection,
 		},
 	}
 
-	// SlickVPN's certificate is sha1WithRSAEncryption and sha1 is now
-	// rejected by openssl 3.x.x which is used by OpenVPN >= 2.5.
-	// We lower the security level to 3 to allow this algorithm,
-	// see https://www.openssl.org/docs/man1.1.1/man3/SSL_CTX_set_security_level.html
-	providerSettings.TLSCipher = "DEFAULT:@SECLEVEL=0"
-
 	return utils.OpenVPNConfig(providerSettings, connection, settings, ipv6Supported)
 }