ci: disable ergo-lib no-default-feature-build

ergo-lib can't be built as a cdylib without an allocator, so disable builds and do check instead

Author: SethDusek

.github/workflows/ci.yml

@@ -24,10 +24,10 @@ jobs:
         with:
           command: build
           args: --no-default-features --manifest-path ergotree-ir/Cargo.toml
-      - name: Build ergo-lib
+      - name: Check ergo-lib
         uses: actions-rs/cargo@v1
         with:
-          command: build
+          command: check
           args: --no-default-features --manifest-path ergo-lib/Cargo.toml
 
   test: