Update version numbers for v4.0 (#59)

### Briefly, what does this PR introduce?
Update version numbers to prepare for the v4.0 tag

### What kind of change does this PR introduce?
- [ ] Bug fix (issue #__)
- [ ] New feature (issue #__)
- [ ] Documentation update
- [X ] Other: version number update

### Please check if this PR fulfills the following:
- [ ] Tests for the changes have been added
- [ ] Documentation has been added / updated
- [ ] Changes have been communicated to collaborators

### Does this PR introduce breaking changes? What changes might users
need to make to their code?

### Does this PR change default behavior?

CMakeLists.txt

@@ -6,9 +6,9 @@ cmake_minimum_required(VERSION 3.12)
 project(EDM4EIC
   LANGUAGES CXX)
 
-SET( ${PROJECT_NAME}_VERSION_MAJOR 3 )
+SET( ${PROJECT_NAME}_VERSION_MAJOR 4 )
 SET( ${PROJECT_NAME}_VERSION_MINOR 0 )
-SET( ${PROJECT_NAME}_VERSION_PATCH 1 )
+SET( ${PROJECT_NAME}_VERSION_PATCH 0 )
 SET( ${PROJECT_NAME}_VERSION  "${${PROJECT_NAME}_VERSION_MAJOR}.${${PROJECT_NAME}_VERSION_MINOR}.${${PROJECT_NAME}_VERSION_PATCH}" )
 
 # C++ standard

edm4eic.yaml

@@ -9,7 +9,7 @@
 ## If there are schema version changes that can be evolved, see the podio documentation
 ## for an example: https://github.com/hegner/podio/blob/master/tests/schema_evolution.yaml
 ##
-schema_version: 301
+schema_version: 400
 
 options :
   # should getters / setters be prefixed with get / set?