Switch to Hugo v0.79.1

The improvements include:
- timezone-aware date formatting
- if getJSON() errors during a build, we can now ignore it
- You can set Hugo configuration via environment variables even if
  snake_case.

Author: Tim Bannister

netlify.toml

@@ -7,7 +7,7 @@ functions = "functions"
 command = "git submodule update --init --recursive --depth 1 && make non-production-build"
 
 [build.environment]
-HUGO_VERSION = "0.74.3"
+HUGO_VERSION = "0.79.1"
 NODE_VERSION = "10.20.0"
 RUBY_VERSION = "2.7.1"