chore(build): disable Solidity workflow

Instead of commenting out the entire file (which results in linter
complaints), use the `if` statement to disable it.

.github/workflows/slither.yml

@@ -10,6 +10,8 @@ on:
 
 jobs:
   analyze:
+    # disabled for now, since we don't have any Solidity files.
+    if: ${{ false }}
     name: Run Slither
     runs-on: ubuntu-latest
     permissions: