CI: Remove -C debuginfo=0 from RUSTFLAGS

Having this flag is preventing tarpaulin from providing us with test coverage reports and I can't find any documented reason for why we would need this.

Author: Turbo87

.github/workflows/ci.yml

@@ -78,7 +78,7 @@ jobs:
       DATABASE_URL: postgres://postgres:postgres@localhost/cargo_registry_test
       TEST_DATABASE_URL: postgres://postgres:postgres@localhost/cargo_registry_test
       CARGO_INCREMENTAL: 0
-      RUSTFLAGS: "-C debuginfo=0 -D warnings"
+      RUSTFLAGS: "-D warnings"
       MALLOC_CONF: "background_thread:true,abort_conf:true,abort:true,junk:true"
 
     services: