docker: add an image to build custom circom for modular Picus

.github/workflows/docker-base-modular-push

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+name: Docker Base Modular Image Push
+
+on: workflow_dispatch
+
+jobs:
+  build-base-docker:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+        with:
+          submodules: 'true'
+          token: ${{ secrets.RELEASE_TOKEN }}
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Login to DockerHub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.SAAS_DOCKERHUB_USERNAME }}
+          password: ${{ secrets.SAAS_DOCKERHUB_TOKEN }}
+      - name: Build and push to DockerHub
+        uses: docker/build-push-action@v3
+        with:
+          context: .
+          push: true
+          file: resources/Dockerfile@base-modular
+          platforms: linux/amd64
+          tags: veridise/picus:base-modular

changelogs/unreleased/23-12-26-custom-circom.yaml

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+added:
+  - Added a Docker image to build a custom circom with the command-flag `--info`
+    which produces an info file for modular reasoning, along with
+    a GitHub Actions workflow to build the image.

resources/Dockerfile@base-modular

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+FROM veridise/picus:base
+
+RUN source "$HOME/.cargo/env" && \
+    git clone https://github.com/sorawee/circom.git && \
+    cd circom/ && \
+    git checkout tag-in-out && \
+    cargo build --release && \
+    cargo install --path circom && \
+    cd .. && rm -rf circom/