📦 Use bundler (#19)

Uses esbuild to bundle the output. This (neglibly) reduces packed size,
but enables better DX for developing css-typed (ex: allows TypeScript).

It does not bundle its dependencies to allow for sharing dependencies in
consumer packages.

|          |  Before |  After | Diff |
| :------: | ------: | -----: | :--: |
|  packed  |  5.8 kB | 4.4 kB | -24% |
| unpacked | 13.7 kB | 9.2 kB | -33% |

Closes #7

Author: connorjs

.github/workflows/pipeline.yaml

@@ -70,7 +70,7 @@ jobs:
           node-version: ${{ matrix.node }}
 
       - name: Install
-        run: npm install --omit=dev
+        run: npm install
 
       - name: Build
         run: npm run build
@@ -113,13 +113,10 @@ jobs:
           registry-url: https://registry.npmjs.org
 
       - name: Set version
-        run: |
-          expr='s/0.0.0-gitversion/${{ env.GitVersion_SemVer }}/g'
-          sed -i "$expr" package.json
-          sed -i "$expr" src/version.js
+        run: sed -i 's/0.0.0-gitversion/${{ env.GitVersion_SemVer }}/g' package.json
 
       - name: Install
-        run: npm install --omit=dev
+        run: npm install
 
       - name: Publish
         run: npm publish --provenance --access public