add build for custom docker container

.gitlab-ci.yml

+default:
+  image: docker:26.0.1
+  services:
+    - docker:26.0.1-dind
+  before_script:
+    - docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+  interruptible: true
+
+stages:
+  - build
+
+s5cmd-partition-build:
+  stage: build
+  script:
+    - docker pull $CI_REGISTRY_IMAGE/s5cmd_dask:latest || true
+    - docker build --cache-from $CI_REGISTRY_IMAGE/s5cmd_dask:latest --tag $CI_REGISTRY_IMAGE/s5cmd_dask:$CI_COMMIT_SHA --tag $CI_REGISTRY_IMAGE/s5cmd_dask:latest -f prep-parquet-for-s5cmd/Dockerfile .
+    - docker push $CI_REGISTRY_IMAGE/s5cmd_dask:$CI_COMMIT_SHA
+    - docker push $CI_REGISTRY_IMAGE/s5cmd_dask:latest

prep-parquet-for-s5cmd/Dockerfile

+FROM daskdev/dask:2024.8.0-py3.11
+
+RUN conda install conda-forge::s5cmd
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