Don't resolve latest sortition-pools contracts

In one of previous commits (581e957) we updated `package.json` and
`package-lock.json` to use fixed version of `sortition-pools` package as
a dependency. We want to use that fixed version also when building an npm
package with `keep-ecdsa` contracts for development environment.

Author: michalinacienciala

.github/workflows/npm.yml

@@ -32,9 +32,7 @@ jobs:
       - name: Resolve latest contracts
         working-directory: ./solidity
         run: |
-          npm update --save-exact \
-            @keep-network/keep-core \
-            @keep-network/sortition-pools
+          npm update --save-exact @keep-network/keep-core
 
       - name: Compile contracts
         run: npx truffle compile