Update to a version that doesn't copy descriptions of subschemas.

Fixes #366.

remove checks for URI scheme; nothing in the spec requires one

# Background

When adding resource templates, we are currently doing checks for
schemes on absolute uris. It is still common for MCP servers to use
custom uris that would not pass these checks. For example, if the
official GitHub MCP server were to use this sdk, it would show failures
like:

```
"repo://{owner}/{repo}/contents{/path*}": parse "repo://{owner}/{repo}/contents{/path*}": invalid character "{" in host name
"repo://{owner}/{repo}/refs/heads/{branch}/contents{/path*}": parse "repo://{owner}/{repo}/refs/heads/{branch}/contents{/path*}": invalid character "{" in host name
"repo://{owner}/{repo}/sha/{sha}/contents{/path*}": parse "repo://{owner}/{repo}/sha/{sha}/contents{/path*}": invalid character "{" in host name
invalid resource template uri "repo://{owner}/{repo}/refs/pull/{prNumber}/head/contents{/path*}": parse "repo://{owner}/{repo}/refs/pull/{prNumber}/head/contents{/path*}": invalid character "{" in host name
"repo://{owner}/{repo}/refs/tags/{tag}/contents{/path*}": parse "repo://{owner}/{repo}/refs/tags/{tag}/contents{/path*}": invalid character "{" in host name
```

The wikipedia MCP would also show problems with missing schemes.

```
"/search/{query}": <nil>
"/article/{title}": <nil>
"/summary/{title}": <nil>
"/summary/{title}/query/{query}/length/{max_length}": <nil>
"/summary/{title}/section/{section_title}/length/{max_length}": <nil>
"/sections/{title}": <nil>
"/links/{title}": <nil>
"/facts/{title}/topic/{topic_within_article}/count/{count}": <nil>
"/coordinates/{title}": <nil>
```

Tools shouldn't both set StructuredContent and return a typed output.
Remove the assignment.

For better organization.

Signed-off-by: Takeshi Yoneda <t.y.mathetake@gmail.com>

Signed-off-by: Takeshi Yoneda <t.y.mathetake@gmail.com>

The Complete handler was returning an abstract Result type, rather than concrete CompleteResult type.

Fixes #375

This CL utilizes the event store to write outgoing messages and removes
the unbounded outgoing data structure.

It also adds a new interface [EventStore.Open]

For #190

Add a loadtest client example, to help confirm performance of our
streamable transport implementation.

For #190