Restore git for version info in CI builds

Dockerfile

@@ -33,6 +33,7 @@ RUN apk add --no-cache --virtual .build-deps \
       python3-dev \
       libffi-dev \
       build-base \
+      git \
   && apk add --no-cache \
       py3-virtualenv \
       py3-pillow \

mautrix_telegram/get_version.py

@@ -15,12 +15,7 @@ cmd_env = {
 def run(cmd):
     return subprocess.check_output(cmd, stderr=subprocess.DEVNULL, env=cmd_env)
 
-if os.environ.get("CI_SERVER", "no") == "yes":
-    git_revision = os.environ["CI_COMMIT_SHA"]
-    git_revision_url = f"https://github.com/tulir/mautrix-telegram/commit/{git_revision}"
-    git_revision = git_revision[:8]
-    git_tag = os.environ.get("CI_COMMIT_TAG", None)
-elif os.path.exists(".git") and shutil.which("git"):
+if os.path.exists(".git") and shutil.which("git"):
     try:
         git_revision = run(["git", "rev-parse", "HEAD"]).strip().decode("ascii")
         git_revision_url = f"https://github.com/tulir/mautrix-telegram/commit/{git_revision}"