prepares next version, raises git/checkout action to v3 (#365)

Author: uklimaschewski

.github/workflows/publish.yml

@@ -7,7 +7,7 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           fetch-depth: 0
       - name: Set up Java for publishing to Maven Central Repository

pom.xml

@@ -5,7 +5,7 @@
 
   <groupId>com.ezylang</groupId>
   <artifactId>EvalEx</artifactId>
-  <version>3.0.3</version>
+  <version>3.0.4-SNAPSHOT</version>
 
   <name>EvalEx</name>