Making quarkus version as env variable

[kameshsampath]

Making Quarkus version as environment variable, as that helps in the commands like to be easy to maintain during release updates:

mvn io.quarkus:quarkus-maven-plugin:$QUARKUS_VERSION:create \
  -DprojectGroupId="com.example" \
  -DprojectArtifactId="fruits-app" \
  -DprojectVersion="1.0-SNAPSHOT" \
  -DclassName="FruitResource" \
  -Dpath="fruit"```