ci: fixes

.woodpecker/cargo-checks.yml

@@ -5,6 +5,6 @@ when:
       ignore_message: "[ALL]"
 steps:
   update:
-    image: rustlang/rust:nightly
+    image: rustlang/rust
     commands: |
-      cargo +nightly fmt -- --check
+      cargo fmt -- --check

.woodpecker/flake-update.yml

@@ -37,10 +37,9 @@ steps:
       owner: ${CI_REPO_OWNER}
       repo: ${CI_REPO_NAME}
       branch: flake-lock-update
-      base_branch: master
+      base_branch: init-ci
       pr_title: "flake.lock: update"
       pr_body: PR automatically created by Woodpecker CI
-      skip_on_missing_branch: false
       close_pr_if_empty: true
       delete_branch_if_pr_empty: true
       merge_when_checks_succeed: false