Fix Qt::SkipEmptyParts deprecation warning (#3726)

Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/messages/search/AuthorPredicate.cpp

@@ -1,5 +1,7 @@
 #include "messages/search/AuthorPredicate.hpp"
 
+#include "util/Qt.hpp"
+
 namespace chatterino {
 
 AuthorPredicate::AuthorPredicate(const QStringList &authors)
@@ -8,7 +10,7 @@ AuthorPredicate::AuthorPredicate(const QStringList &authors)
     // Check if any comma-seperated values were passed and transform those
     for (const auto &entry : authors)
     {
-        for (const auto &author : entry.split(',', QString::SkipEmptyParts))
+        for (const auto &author : entry.split(',', Qt::SkipEmptyParts))
         {
             this->authors_ << author;
         }

src/messages/search/ChannelPredicate.cpp

@@ -1,5 +1,7 @@
 #include "messages/search/ChannelPredicate.hpp"
 
+#include "util/Qt.hpp"
+
 namespace chatterino {
 
 ChannelPredicate::ChannelPredicate(const QStringList &channels)
@@ -8,7 +10,7 @@ ChannelPredicate::ChannelPredicate(const QStringList &channels)
     // Check if any comma-seperated values were passed and transform those
     for (const auto &entry : channels)
     {
-        for (const auto &channel : entry.split(',', QString::SkipEmptyParts))
+        for (const auto &channel : entry.split(',', Qt::SkipEmptyParts))
         {
             this->channels_ << channel;
         }

src/messages/search/LinkPredicate.cpp

@@ -1,5 +1,7 @@
 #include "messages/search/LinkPredicate.hpp"
+
 #include "common/LinkParser.hpp"
+#include "util/Qt.hpp"
 
 namespace chatterino {
 
@@ -9,8 +11,7 @@ LinkPredicate::LinkPredicate()
 
 bool LinkPredicate::appliesTo(const Message &message)
 {
-    for (const auto &word :
-         message.messageText.split(' ', QString::SkipEmptyParts))
+    for (const auto &word : message.messageText.split(' ', Qt::SkipEmptyParts))
     {
         if (LinkParser(word).hasMatch())
             return true;

src/messages/search/MessageFlagsPredicate.cpp

@@ -1,12 +1,14 @@
 #include "messages/search/MessageFlagsPredicate.hpp"
 
+#include "util/Qt.hpp"
+
 namespace chatterino {
 
 MessageFlagsPredicate::MessageFlagsPredicate(const QString &flags)
     : flags_()
 {
     // Check if any comma-seperated values were passed and transform those
-    for (const auto &flag : flags.split(',', QString::SkipEmptyParts))
+    for (const auto &flag : flags.split(',', Qt::SkipEmptyParts))
     {
         if (flag == "deleted" || flag == "disabled")
         {