_content/blog: add go1.19
_content/blog: add go1.19

Announce Go 1.19 (to be posted with the release, planned for August 2).

Change-Id: I82dcde83baca44bf3f4ff2fc28126c3a7a445dbc
Reviewed-on: https://go-review.googlesource.com/c/website/+/420014
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@google.com>
Run-TryBot: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
Reviewed-by: Emmanuel Odeke <bd234ba4276433f0e5fc7a8fa2d18274fa711567@orijtech.com>
Auto-Submit: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Eli Bendersky <e83e4a9813852caf164372e4b6bd506b7819d6ab@google.com>

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website