rename snapshot version from 3.0-SNAPSHOT to 3-SNAPSHOT

[wey-gu]

as title, or other names that won't cause confusion.

[wey-gu]

@Nicole00 what do you think, please?

[wey-gu]

as title, or other names that won't cause confusion.

more queries from WeChat group:

• NebulaGraph 讨论群 · Venus-2023-W6 nebula-community#316 (comment)
• https://community-chat.nebula-graph.io/t/8804884/gt-deer-x-snapshot-jar

[Nicole00]

@Nicole00 what do you think, please?

the name of snapshot keeps consistent with client. I agree with the 3-SNAPSHOT. And more understandable name is 3.3-SNAPSHOT, 3.4-SNAPSHOT. But we will not maintain every sub-branch so frequently for lack of human resource, so just maintain the x major version to update the snapshot.
cc @MuYiYong