fix: resolve release-please workspace member detection

- Remove explicit '.' from Cargo workspace members — root package is
  implicit when [workspace] and [package] coexist in the same manifest.
  release-please's cargo-workspace plugin was warning 'member . declared
  but did not find Cargo.toml', causing git-rewrite's [package].version
  to not be written to Cargo.toml in release PRs.

- Remove redundant extra-files block for plumbing/git-filter-tree.
  The path '/Cargo.toml' had a spurious leading slash, and the update
  it was trying to make (dependencies.git-filter-tree.version) is
  already handled automatically by the cargo-workspace plugin.

Author: jdc-pub

.config/release-please-config.json

@@ -14,15 +14,7 @@
       "include-component-in-tag": false,
       "exclude-paths": ["plumbing/"]
     },
-    "plumbing/git-filter-tree": {
-      "extra-files": [
-        {
-          "type": "toml",
-          "path": "/Cargo.toml",
-          "jsonpath": "$.dependencies.git-filter-tree.version"
-        }
-      ]
-    }
+    "plumbing/git-filter-tree": {}
   },
   "plugins": [{ "type": "sentence-case" }, { "type": "cargo-workspace" }],
   "$schema": "https://raw.githubusercontent.com/googleapis/release-please/main/schemas/config.json"

Cargo.toml

@@ -1,6 +1,6 @@
 [workspace]
 resolver = "3"
-members = [".", "plumbing/git-filter-tree"]
+members = ["plumbing/git-filter-tree"]
 
 [workspace.package]
 edition = "2024"