basic: Telegram CI notification has empty commit, branch and time #39

The Telegram step in .github/workflows/build.yml on basic uses ${GIT_HASH}, ${GIT_BRANCH}, ${TAG_NAME} and ${TIME}, but never sets them. (The v2 workflow sets all four at the start of the step.) The notification therefore arrives as Commit: \nBranch: \n....

Fix: copy the four variable definitions from the v2 workflow.