ios: sign with disposable login keychain

.gitea/workflows/testflight-release.yml

@@ -91,7 +91,7 @@ jobs:
           developer_dir="$(xcode-select -p)"
           signing_dir="$(mktemp -d "${RUNNER_TEMP:-${TMPDIR:-/tmp}}/sybil-signing.XXXXXX")"
           mkdir -p "${HOME}/Library/Keychains"
-          keychain_name="${HOME}/Library/Keychains/${SIGNING_KEYCHAIN}-${GITHUB_RUN_ID:-$(uuidgen)}.keychain"
+          keychain_name="${HOME}/Library/Keychains/login.keychain"
           certificate_path="${signing_dir}/appstore-signing.p12"
           wwdr_certificate_path="${signing_dir}/AppleWWDRCAG3.cer"
           profile_path="${signing_dir}/Sybil_AppStore_CI.mobileprovision"