build and poetry: the 1970s are calling

[ThomasWaldmann]

poetry uses 1970 timestamps in the sdist by default:

(pkgconfig-env) tw@MacBook-Pro pkgconfig % python3 -m build     
* Creating isolated environment: venv+pip...
* Installing packages in isolated environment:
  - poetry_core>=1.0.0
* Getting build dependencies for sdist...
* Building sdist...
* Building wheel from sdist
* Creating isolated environment: venv+pip...
* Installing packages in isolated environment:
  - poetry_core>=1.0.0
* Getting build dependencies for wheel...
* Building wheel...
Successfully built pkgconfig-1.6.0.tar.gz and pkgconfig-1.6.0-py3-none-any.whl

tw@MacBook-Pro dist % tar tzvf dist/pkgconfig-1.6.0.tar.gz 
-rw-r--r--  0 0      0        1097 Jan  1  1970 pkgconfig-1.6.0/LICENSE
-rw-r--r--  0 0      0        3892 Jan  1  1970 pkgconfig-1.6.0/README.rst
-rw-r--r--  0 0      0         954 Jan  1  1970 pkgconfig-1.6.0/pyproject.toml
-rw-r--r--  0 0      0          25 Jan  1  1970 pkgconfig-1.6.0/src/pkgconfig/__init__.py
-rw-r--r--  0 0      0        9161 Jan  1  1970 pkgconfig-1.6.0/src/pkgconfig/pkgconfig.py
-rw-r--r--  0 0      0        4833 Jan  1  1970 pkgconfig-1.6.0/PKG-INFO

To get the current date in there:

(pkgconfig-env) tw@MacBook-Pro pkgconfig % SOURCE_DATE_EPOCH=$(git log -1 --format=%ct) python3 -m build
* Creating isolated environment: venv+pip...
* Installing packages in isolated environment:
  - poetry_core>=1.0.0
* Getting build dependencies for sdist...
* Building sdist...
* Building wheel from sdist
* Creating isolated environment: venv+pip...
* Installing packages in isolated environment:
  - poetry_core>=1.0.0
* Getting build dependencies for wheel...
* Building wheel...
Successfully built pkgconfig-1.6.0.tar.gz and pkgconfig-1.6.0-py3-none-any.whl

(pkgconfig-env) tw@MacBook-Pro pkgconfig % tar tzvf dist/pkgconfig-1.6.0.tar.gz 
-rw-r--r--  0 0      0        1097 Mar  6 00:22 pkgconfig-1.6.0/LICENSE
-rw-r--r--  0 0      0        3892 Mar  6 00:22 pkgconfig-1.6.0/README.rst
-rw-r--r--  0 0      0         954 Mar  6 00:22 pkgconfig-1.6.0/pyproject.toml
-rw-r--r--  0 0      0          25 Mar  6 00:22 pkgconfig-1.6.0/src/pkgconfig/__init__.py
-rw-r--r--  0 0      0        9161 Mar  6 00:22 pkgconfig-1.6.0/src/pkgconfig/pkgconfig.py
-rw-r--r--  0 0      0        4833 Mar  6 00:22 pkgconfig-1.6.0/PKG-INFO