bump a few deps

In particular, allow/require latest major of these in `Cargo.toml`:

* `base64`
* `criterion` (dev only)
* `h264-reader`
* `pretty-hex`
* `rtsp-types`
* `webrtc` (example only)

...and since that pulls in stuff with a minimum Rust of 1.67, bump to
that. Strictly speaking I think it's only dev that requires that now,
but it's old enough that requiring it should be no problem.

I held off on upgrading `bitstream-io` to 2, because the latest
`h264-reader` still uses v1, and I like to minimize how much duplication
I require.

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
       matrix:
         rust:
           - stable
-          - 1.64
+          - 1.67
         include:
           - rust: stable
             extra_components: rustfmt

CHANGELOG.md

@@ -13,6 +13,7 @@
 *   customizable behavior for RTCP packets with unknown ssrcs, now defaulting to
     ignoring them. This also is necessary to interoperate with the Tapo C320WS.
 *   improve some incorrect, misleading, and/or uninformative logging.
+*   minimum Rust is now 1.67.
 
 ## `v0.4.5` (2023-02-02)