Followed installation instructions. Checked out amaranth-boards into my working directory. Created the LEDBlinker and LEDBlinker build scripts from "Getting Started" and ran
```
PYTHONPATH=amaranth-boards pypy3 am_blink_build.py
```
Got this error on the mere fact of importing from icestick
```
nostromo:am_tests mcc$ PYTHONPATH=amaranth-boards pypy3 am_blink_build.py 
Traceback (most recent call last):
  File "/Users/mcc/work/f/am_tests/am_blink_build.py", line 1, in <module>
    from amaranth_boards.icestick import *
  File "/Users/mcc/work/f/am_tests/amaranth-boards/amaranth_boards/icestick.py", line 4, in <module>
    from amaranth.build import *
  File "/Users/mcc/.local/lib/pypy3.10/site-packages/amaranth/build/__init__.py", line 3, in <module>
    from .plat import *
  File "/Users/mcc/.local/lib/pypy3.10/site-packages/amaranth/build/plat.py", line 6, in <module>
    import jinja2
  File "/Users/mcc/.local/lib/pypy3.10/site-packages/jinja2/__init__.py", line 12, in <module>
    from .environment import Environment
  File "/Users/mcc/.local/lib/pypy3.10/site-packages/jinja2/environment.py", line 25, in <module>
    from .defaults import BLOCK_END_STRING
  File "/Users/mcc/.local/lib/pypy3.10/site-packages/jinja2/defaults.py", line 3, in <module>
    from .filters import FILTERS as DEFAULT_FILTERS  # noqa: F401
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/mcc/.local/lib/pypy3.10/site-packages/jinja2/filters.py", line 13, in <module>
    from markupsafe import soft_unicode
ImportError: cannot import name 'soft_unicode' from 'markupsafe' (/Users/mcc/.local/lib/pypy3.10/site-packages/markupsafe/__init__.py)

```
Is this surprising?
Do I need to install anything else?