[chore] add woodpecker ci/cd pipelines (#4061)

Removes our now unused drone stuff and adds pipelines for our new woodpecker instance.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4061
Co-authored-by: tobi <tobi.smethurst@protonmail.com>
Co-committed-by: tobi <tobi.smethurst@protonmail.com>

.woodpecker/release.yaml

@@ -0,0 +1,41 @@
+# https://woodpecker-ci.org/docs/usage/workflow-syntax#when---global-workflow-conditions
+when:
+  - event: push
+    branch: main
+
+steps:
+  release:
+    # https://github.com/superseriousbusiness/gotosocial-drone-build
+    image: superseriousbusiness/gotosocial-drone-build:0.8.0
+    pull: true
+
+    # https://woodpecker-ci.org/docs/usage/volumes
+    volumes:
+      - /woodpecker/gotosocial/go-build-cache-root:/root/.cache/go-build
+      - /woodpecker/gotosocial/go-pkg-cache-root:/go/pkg
+      - /var/run/docker.sock:/var/run/docker.sock
+
+    # https://woodpecker-ci.org/docs/usage/environment
+    # https://woodpecker-ci.org/docs/usage/secrets#usage
+    environment:
+      DOCKER_USERNAME: gotosocial
+      DOCKER_PASSWORD:
+        from_secret: gts_docker_password
+      GITHUB_TOKEN:
+        from_secret: github_token
+    
+    # https://woodpecker-ci.org/docs/usage/workflow-syntax#commands
+    commands:
+      - git fetch --tags
+      - /go/dockerlogin.sh
+      
+      # When releasing, compare commits to the most recent tag that is not the
+      # current one AND is not a release candidate tag (ie., no "rc" in the name).
+      #
+      # The DRONE_TAG env var should point to the tag that triggered this build.
+      # See: https://docs.drone.io/pipeline/environment/reference/drone-tag/ 
+      #
+      # Note, this may cause annoyances when doing backport releases, for example,
+      # releasing v0.10.1 when we've already released v0.15.0 or whatever, but
+      # they should only be superficial annoyances related to the release notes.
+      - GORELEASER_PREVIOUS_TAG=$(git tag -l | grep -v "rc\|${DRONE_TAG}" | sort -V -r | head -n 1) goreleaser release --clean