Version 0.7.1 fixes an issue with the Ant buildpack.

### Fixed

-  The `ant` buildpack uses the official Apache Ant archives instead of the
   sonic.net mirror. The Apache Ant archives hold all the releases of Ant, not
   just the latest few versions.

Write 0.7 release summary

Map Docker architecture values to biome values (#318)

[Fixes ch5015]

Don't use Docker if resource has a `YB_CONTAINER_*_IP` environment va…

…riable set (#315)

[Fixes ch4961]

Permit environment sections to be maps instead of lists (#305)

Lists are still permitted for backward compatibility. I've updated the
docs to use the new map style, as it's a better fit for YAML structures.

[Fixes ch4916]

Make output more compact and easier to read (#295)

Build output now includes a target and command heading. Info-level log
lines no longer have the unhelpful "INFO" prefix. All non-error build
output now goes to stdout so someone who wants a more quiet experience
for a successful build can redirect to `/dev/null`.

Individual lines of command and log output now also include the target
they are running for and the time the line was outputted. This serves to
both visually group outputs by command as well as provide fine-grained
timing information.

Also propagate `NO_COLOR` to build environment.

[Fixes ch4043]
[Fixes ch4040]

Version 0.6.3 changes the build environment keychain name.

### Changed

-  On macOS, the empty, default keychain that yb creates will now be called
   `login` instead of `yb` for compatibility with more programs.

Version 0.5.8 backports a change to the build environment keychain name.

### Changed

-  On macOS, the empty, default keychain that yb creates will now be called
   `login` instead of `yb` for compatibility with more programs.

Version 0.6.2 fixes a locale environment variable issue and improves …

…the output

for builds with containers that don't start up.

### Changed

-  The build environment now sets `LANG` and other locale environment variables
   to `C.UTF-8` or the closest approximation thereof. Previously, these
   variables were unset, which caused problems with programs that required a
   UTF-8 character set to function properly, like those written in Ruby or Python.

### Fixed

-  If a container dependency exits while waiting for it to become healthy,
   yb will now display a container's logs rather than waiting for the full
   timeout and giving an unhelpful error message.
-  The `TZ` environment variable is now set to `UTC0` by default. Previously,
   it was set to `UTC`, which is not a POSIX-conforming value.

Version 0.5.7 backports a fix for a locale environment variable issue.

### Changed

-  The build environment now sets `LANG` and other locale environment variables
   to `C.UTF-8` or the closest approximation thereof. Previously, these
   variables were unset, which caused problems with programs that required a
   UTF-8 character set to function properly, like those written in Ruby or Python.

### Fixed

-  The `TZ` environment variable is now set to `UTC0` by default. Previously,
   it was set to `UTC`, which is not a POSIX-conforming value.