add cache to ci

.drone.yml

@@ -3,11 +3,25 @@ type: docker
 name: default
 
 steps:
+- name: restore-cache-with-filesystem
+  image: meltwater/drone-cache
+  settings:
+    backend: "filesystem"
+    restore: true
+    cache_key: "{{ .Repo.Name }}"
+    archive_format: "gzip"
+    filesystem_cache_root: "/tmp/cache"
+    mount:
+      - '.pipcache'
+  volumes:
+  - name: cache
+    path: /tmp/cache
+
 - name: static_analysis
   image: python:3.8
   commands:
-  - pip3 install pylint bandit mccabe
-  - pip3 install -r requirements.txt
+  - pip3 install --cache-dir='./.pipcache' pylint bandit mccabe
+  - pip3 install --cache-dir='./.pipcache' -r requirements.txt
   - find . -name "*.py" -exec python3 -m py_compile '{}' \;
   - find . -name "*.py" -exec pylint '{}' + || if [ $? -eq 1 ]; then echo "you fail"; fi
   - find . -name "*.py" -exec python3 -m mccabe --min 3 '{}' + || if [ $? -eq 1 ]; then echo "you fail"; fi
@@ -42,6 +56,23 @@ steps:
   - cd docs
   - make html
 
+- name: rebuild-cache-with-filesystem
+  image: meltwater/drone-cache
+  pull: true
+  settings:
+    backend: "filesystem"
+    rebuild: true
+    cache_key: "{{ .Repo.Name }}"
+    archive_format: "gzip"
+    filesystem_cache_root: "/tmp/cache"
+    mount:
+      - '.pipcache'
+  volumes:
+  - name: cache
+    path: /tmp/cache
+
+
+
 - name: build_docs
   image: docker:stable-dind
   volumes: