chore: publish metadata as gitlab artifact (#459)

## fixes KILTprotocol/ticket#2241
Generates metadata and publishes json value to s3 bucket
Sample here https://kilt-protocol.org/peregrine/peregrine-metadata.json

## Pending

- [x] SRTool Docker image that includes the new subwasm 0.19 with
support for `json+scale` output format. PR:
paritytech/srtool#60

---------

Co-authored-by: Tino Rusch <tino@kilt.io>
Co-authored-by: Antonio <antonio@kilt.io>

.gitlab-ci.yml

@@ -65,7 +65,7 @@ build:
 
 build-wasm-peregrine:
   image:
-    name: paritytech/srtool:1.66.1-0.9.25
+    name: paritytech/srtool:1.69.0
     entrypoint: [""]
   stage: build
   only:
@@ -79,16 +79,18 @@ build-wasm-peregrine:
     - export AUTHORIZE_UPGRADE_PREFIX=0x02
     - cp -r * /build
     - /srtool/build build
+    - subwasm meta --format=json+scale /out/peregrine_runtime.compact.wasm > /out/peregrine-metadata.json
     - mkdir ./out
     - mv /out/* ./out/
   artifacts:
     paths:
       - out/*.wasm
+      - out/*.json
     expire_in: 12 week
 
 build-wasm-spiritnet:
   image:
-    name: paritytech/srtool:1.66.1-0.9.25
+    name: paritytech/srtool:1.69.0
     entrypoint: [""]
   stage: build
   only:
@@ -102,9 +104,11 @@ build-wasm-spiritnet:
     - export AUTHORIZE_UPGRADE_PREFIX=0x02
     - cp -r * /build
     - /srtool/build build
+    - subwasm meta --format=json+scale /out/spiritnet_runtime.wasm > /out/spiritnet-metadata.json
     - mkdir ./out
     - mv /out/* ./out/
   artifacts:
     paths:
       - out/*.wasm
+      - out/*.json
     expire_in: 12 week