Don't write stdout and stderr in parallel

[luke-engle]

What's changing?

gh valet was writing stdout and stderr to the console in parallel. This meant if there was an error that happened while we were writing to stdout, we got mangled text in the console. For example: WARNING! Your password will be stored unencLogin rypted in /home/codespace/.dockerSucceeded.

This change adds a lock to the ReadStream method to prevent both streams from writing at the same time.

How's this tested?

Before this change 👇

➜ echo "<GH PAT>" | gh valet update --username luke-engle --password-stdin                                      
LWAogin SucceeRded
NING! Your password will be stored unencrypted in /Users/lukeengle/.docker/config.json.
Configure a credential helper to remove this warning. See
https://docs.docker.com/engine/reference/commandline/login/#credentials-store

latest: Pulling from valet-customers/valet-cli
...

After this change 👇

➜ echo "<GH PAT>" | dotnet run --project src/Valet/Valet.csproj -- update --username luke-engle --password-stdin
WARNING! Your password will be stored unencrypted in /Users/lukeengle/.docker/config.json.
Configure a credential helper to remove this warning. See
https://docs.docker.com/engine/reference/commandline/login/#credentials-store

Login Succeeded
latest: Pulling from valet-customers/valet-cli
...

Closes #79

[github-actions[bot]]

Unit Test Results

35 tests  ±0   35 :heavy_check_mark: ±0   0s :stopwatch: ±0s   1 suites ±0     0 :zzz: ±0    1 files   ±0     0 :x: ±0 

Results for commit e99732c5. ± Comparison against base commit 57d429d9.

:recycle: This comment has been updated with latest results.