fix(ci): repair mangled deno-lint guard (#24)

Previous PR #23's sed corrupted the run: line (sed treated 2>&1's & as
the match). Replaces with a clean find-based guard.

Author: hyperpolymath

.github/workflows/rescript-deno-ci.yml

@@ -21,7 +21,7 @@ jobs:
           deno-version: v1.x
 
       - name: Deno lint
-        run: 'if ls **/*.ts >/dev/null 2>run: deno lint1 || ls *.ts >/dev/null 2>run: deno lint1; then deno lint; else echo "no TS sources to lint"; fi'
+        run: if find . -name "*.ts" -not -path "./.git/*" | grep -q .; then deno lint; else echo "no TS sources to lint"; fi
 
       - name: Deno fmt check
         run: deno fmt --check