Go: Fix ZAddIncr Return Type

[edlng]

Issue

Command returns a nil or int, but doc doesnt say when null is returned.

PR Description

In reality, ZAddIncr without options will never return nil. This aligns with the Java client's implementation. We should update it to reflect this fact.

valkey-glide/java/client/src/main/java/glide/api/BaseClient.java

Lines 2059 to 2067 in 184772b

	@Override
	public CompletableFuture<Double> zaddIncr(
	@NonNull String key, @NonNull String member, double increment) {
	String[] arguments =
	concatenateArrays(
	new String[] {key}, new String[] {"INCR", Double.toString(increment), member});
	return commandManager.submitNewCommand(ZAdd, arguments, this::handleDoubleResponse);
	}

Issue link

This Pull Request is linked to issue (URL): #4070

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one issue.
• Commit message has a detailed description of what changed and why.
• Tests are added or updated.
• CHANGELOG.md and documentation files are updated.
• Destination branch is correct - main or release
• Create merge commit if merging release branch into main, squash otherwise.