Try removing build-base from CI to simplify if possible

Seems like the scripts we're based on for ACT are no longer maintained
and Chrome's automateable download flow has changed quite a bit, so
things are starting to break. Can we get away without it?

.github/workflows/ci.yml

@@ -4,7 +4,6 @@ jobs:
   build:
     name: Build & test
     runs-on: ubuntu-latest
-    container: httptoolkit/act-build-base:v3.0.0
     steps:
       - uses: actions/checkout@v3
 
@@ -50,7 +49,6 @@ jobs:
     name: Check for new blog posts to announce
     if: github.event_name == 'push'
     runs-on: ubuntu-latest
-    container: httptoolkit/act-build-base:v3.0.0
     needs: build
     outputs:
       new-blog-post: ${{ steps.detect-changes.outputs.new-blog-post }}
@@ -98,7 +96,6 @@ jobs:
     name: Build & publish container to Docker Hub
     if: github.event_name == 'push' && !startsWith(github.ref, 'refs/heads/dependabot/')
     runs-on: ubuntu-latest
-    container: httptoolkit/act-build-base
     needs: build
     steps:
       - uses: actions/checkout@v3
@@ -138,7 +135,6 @@ jobs:
     name: Deploy to Scaleway
     if: github.event_name == 'push' && github.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
-    container: httptoolkit/act-build-base:v3.0.0
     needs: publish-docker
     steps:
       - name: Redeploy container
@@ -165,7 +161,6 @@ jobs:
     name: Announce new blog posts
     if: github.event_name == 'push' && github.ref == 'refs/heads/main' && needs.check-blog-changes.outputs.new-blog-post != ''
     runs-on: ubuntu-latest
-    container: httptoolkit/act-build-base:v3.0.0
     needs:
       - check-blog-changes
       - publish-scaleway