ci: bump ci image to rust 1.73.0 (#1830)

Co-authored-by: command-bot <>

.gitlab/pipeline/build.yml

@@ -91,6 +91,7 @@ build-rustdoc:
     - .run-immediately
   variables:
     SKIP_WASM_BUILD: 1
+    RUSTDOCFLAGS: ""
   artifacts:
     name: "${CI_JOB_NAME}_${CI_COMMIT_REF_NAME}-doc"
     when: on_success
@@ -99,7 +100,6 @@ build-rustdoc:
       - ./crate-docs/
   script:
     # FIXME: it fails with `RUSTDOCFLAGS="-Dwarnings"` and `--all-features`
-    # FIXME: return to stable when https://github.com/rust-lang/rust/issues/96937 gets into stable
     - time cargo doc --features try-runtime,experimental --workspace --no-deps
     - rm -f ./target/doc/.lock
     - mv ./target/doc ./crate-docs

.gitlab/pipeline/test.yml

@@ -181,7 +181,6 @@ test-rustdoc:
     - .run-immediately
   variables:
     SKIP_WASM_BUILD: 1
-    RUSTDOCFLAGS: "-Dwarnings"
   script:
     - time cargo doc --workspace --all-features --no-deps
   allow_failure: true