Use an SSH URL to fetch Runtime in CI

[czechboy0]

(Same as: https://github.com/apple/swift-openapi-generator/pull/3)

Motivation

Until the swift-openapi-runtime repository is made public, it cannot be cloned using a HTTPS package URL without authentication, which is what this package is using in its Package.swift.

This means CI isn't able to run for this package. However, CI is able to clone this repository over SSH, which presents an opportunity for a temporary workaround.

Modifications

Add a temporary step to the Docker Compose CI flow, which creates a Git config in a shared ephemeral volume with the following contents:

[url "git@github.com:apple/swift-openapi-runtime"]
        insteadOf = https://github.com/apple/swift-openapi-runtime

Result

The CI should be able to clone the private dependency and then succeed.

Test Plan

Locally, this works:

❯ docker-compose -f docker/docker-compose.yaml -f docker/docker-compose.2204.58.yaml run test
...
+ swift test -Xswiftc -warnings-as-errors --explicit-target-dependency-import-check error
...
Fetching https://github.com/apple/swift-openapi-runtime
...
Fetched https://github.com/apple/swift-openapi-runtime (2.68s)
...
Executed 86 tests, with 0 failures (0 unexpected) in 3.265 (3.265) seconds

Also, if we use can use the shell Docker Compose service to see things are configured correctly:

root@20ab69e3f292:/code# echo $GIT_CONFIG_GLOBAL
/ci-gitconfig/gitconfig
root@20ab69e3f292:/code# cat $GIT_CONFIG_GLOBAL
[url "git@github.com:apple/swift-openapi-runtime"]
        insteadOf = https://github.com/apple/swift-openapi-runtime

[simonjbeaumont]

//cc @yim-lee