fix(FastAPI): Improve sqlite testing speed

This commit adds a new Arch dependency: `libeatmydata`, which
provides the `eatmydata` executable that stubs out fsync() operations.
We use `eatmydata` to run our sharness and pytests in Docker now.

With `autocommit=True`, required by SQLAlchemy to keep the
session up to date with external DB modifications, many fsync
calls are used in the SQLite backend; especially because we're wiping
and creating records in every DB-bound test.

**Before:**

- mysql: 1m42s (elapsed during pytest run)
- sqlite: 3m06s (elapsed during pytest run)

**After:**

- mysql: 1m40s (elapsed during pytest run)
- sqlite: 1m50s (elapsed during pytest run)

Shout out to @klausenbusk, who suggested this as a possible fix,
and it was. Thanks, Kristian!

Closes #120

Signed-off-by: Kevin Morris <kevr@0cost.org>

docker/scripts/run-sharness.sh

@@ -4,4 +4,4 @@ set -eou pipefail
 # Initialize the new database; ignore errors.
 python -m aurweb.initdb 2>/dev/null || /bin/true
 
-make -C test sh
+eatmydata -- make -C test sh