Refactor port{min,max} to port{Min,Max}

As most variable names are using camelCase.

agent.go

@@ -64,8 +64,8 @@ type Agent struct {
 	prflxAcceptanceMinWait time.Duration
 	relayAcceptanceMinWait time.Duration
 
-	portmin uint16
-	portmax uint16
+	portMin uint16
+	portMax uint16
 
 	candidateTypes []CandidateType
 
@@ -297,8 +297,8 @@ func NewAgent(config *AgentConfig) (*Agent, error) { //nolint:gocognit
 		taskLoopDone:      make(chan struct{}),
 		startedCh:         startedCtx.Done(),
 		startedFn:         startedFn,
-		portmin:           config.PortMin,
-		portmax:           config.PortMax,
+		portMin:           config.PortMin,
+		portMax:           config.PortMax,
 		loggerFactory:     loggerFactory,
 		log:               log,
 		net:               config.Net,

gather.go

@@ -221,7 +221,7 @@ func (a *Agent) gatherCandidatesLocal(ctx context.Context, networkTypes []Networ
 				// is there a way to verify that the listen address is even
 				// accessible from the current interface.
 			case udp:
-				conn, err := listenUDPInPortRange(a.net, a.log, int(a.portmax), int(a.portmin), network, &net.UDPAddr{IP: ip, Port: 0})
+				conn, err := listenUDPInPortRange(a.net, a.log, int(a.portMax), int(a.portMin), network, &net.UDPAddr{IP: ip, Port: 0})
 				if err != nil {
 					a.log.Warnf("could not listen %s %s", network, ip)
 					continue
@@ -334,7 +334,7 @@ func (a *Agent) gatherCandidatesSrflxMapped(ctx context.Context, networkTypes []
 		go func() {
 			defer wg.Done()
 
-			conn, err := listenUDPInPortRange(a.net, a.log, int(a.portmax), int(a.portmin), network, &net.UDPAddr{IP: nil, Port: 0})
+			conn, err := listenUDPInPortRange(a.net, a.log, int(a.portMax), int(a.portMin), network, &net.UDPAddr{IP: nil, Port: 0})
 			if err != nil {
 				a.log.Warnf("Failed to listen %s: %v", network, err)
 				return
@@ -469,7 +469,7 @@ func (a *Agent) gatherCandidatesSrflx(ctx context.Context, urls []*URL, networkT
 					return
 				}
 
-				conn, err := listenUDPInPortRange(a.net, a.log, int(a.portmax), int(a.portmin), network, &net.UDPAddr{IP: nil, Port: 0})
+				conn, err := listenUDPInPortRange(a.net, a.log, int(a.portMax), int(a.portMin), network, &net.UDPAddr{IP: nil, Port: 0})
 				if err != nil {
 					closeConnAndLog(conn, a.log, fmt.Sprintf("Failed to listen for %s: %v", serverAddr.String(), err))
 					return