fix: Removed mandatory GitHub token on artifacts downloading (#1761)

Fixes #1695 

## Test Plan
> How do we know the code works?

Flank should download test artifacts without any exceptions when GitHub token is not set in environment variables.

- [X] Unit tested

flank-scripts/build.gradle.kts

@@ -26,7 +26,7 @@ shadowJar.apply {
     }
 }
 // <breaking change>.<feature added>.<fix/minor change>
-version = "1.9.6"
+version = "1.9.7"
 group = "com.github.flank"
 
 application {

flank-scripts/src/main/kotlin/flank/scripts/data/github/GithubApi.kt

@@ -205,10 +205,12 @@ fun Request.appendGitHubHeaders(githubToken: String, contentType: String = "appl
 fun githubRepo(
     token: String,
     repoPath: String
-): Repo =
-    RtGithub(token)
-        .repos()
-        .get(Coordinates.Simple(repoPath))
+): Repo = createGitHubClient(token).repos().get(Coordinates.Simple(repoPath))
+
+private fun createGitHubClient(gitHubToken: String) = when {
+    gitHubToken.isEmpty() -> RtGithub()
+    else -> RtGithub(gitHubToken)
+}
 
 fun Repo.getRelease(tag: String): Release.Smart? =
     Releases.Smart(releases()).run {

flank-scripts/src/main/kotlin/flank/scripts/ops/testartifacts/Helpers.kt

@@ -17,4 +17,5 @@ val File.testArtifacts: File get() = resolve(TEST_ARTIFACTS_PATH).apply { if (!e
 
 fun File.testArtifacts(branch: String = currentGitBranch()): File = testArtifacts.resolve(branch)
 
-internal fun testArtifactsRepo(): Repo = githubRepo(getEnv(GITHUB_TOKEN_ENV_KEY), flankTestArtifactsRepository)
+internal fun testArtifactsRepo(): Repo =
+    githubRepo(getEnv(GITHUB_TOKEN_ENV_KEY, ""), flankTestArtifactsRepository)

flank-scripts/src/main/kotlin/flank/scripts/utils/Env.kt

@@ -1,6 +1,5 @@
 package flank.scripts.utils
 
-fun getEnv(key: String): String =
-    System.getenv(key) ?: throw RuntimeException("Environment variable '$key' not found!")
-
+fun getEnv(key: String, default: String? = null): String =
+    System.getenv(key) ?: default ?: throw RuntimeException("Environment variable '$key' not found!")
 val isWindows: Boolean = System.getProperty("os.name").startsWith("Windows")

flank-scripts/src/test/kotlin/flank/scripts/ops/testartifacts/TestArtifactsRepoTest.kt

@@ -0,0 +1,18 @@
+package flank.scripts.ops.testartifacts
+
+import flank.scripts.data.github.getRelease
+import flank.scripts.utils.getEnv
+import io.mockk.every
+import io.mockk.mockkStatic
+import org.junit.Test
+
+class TestArtifactsRepoTest {
+
+    @Test
+    fun `should not throw when gh token not set`() {
+        mockkStatic(::getEnv)
+        every { getEnv(any(), any()) } returns ""
+        testArtifactsRepo().getRelease("master")
+            ?.body()?.toLong()
+    }
+}