autoformat cabal file (#1769)

Closes #1709.

.github/workflows/normalize-cabal.yml

@@ -0,0 +1,24 @@
+name: Normalize cabal file formatting
+on:
+  push:
+    paths:
+      - '**.hs'
+      - '**.cabal'
+    branches:
+      - main
+  pull_request:
+    paths:
+      - '**.hs'
+      - '**.cabal'
+    branches:
+      - main
+jobs:
+  gild:
+    name: Normalize cabal
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: tfausak/cabal-gild-setup-action@v1
+        with:
+          version: 0.3.0.1
+      - run: cabal-gild --input swarm.cabal --mode check

scripts/normalize-cabal.sh

@@ -0,0 +1,7 @@
+#!/bin/bash -ex
+
+SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
+cd $SCRIPT_DIR/..
+
+CABAL_FILE=swarm.cabal
+cabal-gild --input $CABAL_FILE --output $CABAL_FILE --mode format