Update SoftwareSerial version to 3.4.1 (#4623)

* Update SoftwareSerial version to 3.4.1

Author: plerup

package/build_boards_manager_package.sh

@@ -61,7 +61,7 @@ rm exclude.txt
 # Get additional libraries (TODO: add them as git submodule or subtree?)
 
 # SoftwareSerial library
-curl -L -o SoftwareSerial.zip https://github.com/plerup/espsoftwareserial/archive/3.3.1.zip
+curl -L -o SoftwareSerial.zip https://github.com/plerup/espsoftwareserial/archive/3.4.1.zip
 unzip -q SoftwareSerial.zip
 rm -rf SoftwareSerial.zip
 mv espsoftwareserial-* SoftwareSerial