add the ability to specify repository ref (#80)

closes #75

Reviewed-on: #80
Co-authored-by: Maxim Slipenko <no-reply@maxim.slipenko.com>
Co-committed-by: Maxim Slipenko <no-reply@maxim.slipenko.com>

internal/translations/po/ru/default.po

@@ -425,19 +425,19 @@ msgstr "Выполнение build()"
 msgid "Executing %s()"
 msgstr "Выполнение %s()"
 
-#: pkg/repos/pull.go:79
+#: pkg/repos/pull.go:80
 msgid "Pulling repository"
 msgstr "Скачивание репозитория"
 
-#: pkg/repos/pull.go:103
+#: pkg/repos/pull.go:116
 msgid "Repository up to date"
 msgstr "Репозиторий уже обновлён"
 
-#: pkg/repos/pull.go:160
+#: pkg/repos/pull.go:207
 msgid "Git repository does not appear to be a valid ALR repo"
 msgstr "Репозиторий Git не поддерживается репозиторием ALR"
 
-#: pkg/repos/pull.go:176
+#: pkg/repos/pull.go:223
 msgid ""
 "ALR repo's minimum ALR version is greater than the current version. Try "
 "updating ALR if something doesn't work."