docker tutorial fails to build

[scottjl]

from: https://pg-auto-failover.readthedocs.io/en/main/tutorial.html

under pre-requisites:

$ git clone https://github.com/hapostgres/pg_auto_failover
$ cd pg_auto_failover/docs/tutorial
$ docker compose build

fails with:

 => ERROR [node2 build 6/7] COPY ./src/bin/pg_autoctl/git-version.h ./src/bin/pg_autoctl/git-version.h                              0.0s
 => CANCELED [node2 run  2/16] RUN apt-get update   && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends    0.0s
 => CANCELED [app  2/10] RUN apt-get update   && apt-get install -y --no-install-recommends      ca-certificates      gnupg      m  0.0s
------
 > [node2 build 6/7] COPY ./src/bin/pg_autoctl/git-version.h ./src/bin/pg_autoctl/git-version.h:

 114 | >>> COPY ./src/bin/pg_autoctl/git-version.h ./src/bin/pg_autoctl/git-version.h

there is no file ./src/bin/pg_autoctl/git-version.h located anywhere.