chore: add rust-toolchain.toml for consistent Rust version usage

Signed-off-by: R. Tyler Croy <rtyler@brokenco.de>

Author: rtyler

Cargo.toml

@@ -5,7 +5,7 @@ resolver = "3"
 
 [workspace.package]
 authors = ["Qingping Hou <dave2008713@gmail.com>", "R Tyler Croy <rtyler@brokenco.de>"]
-rust-version = "1.88"
+rust-version = "1.91"
 keywords = ["deltalake", "delta", "datalake"]
 readme = "README.md"
 edition = "2024"

rust-toolchain.toml

@@ -0,0 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+[toolchain]
+channel = "1.91"
+components = ["rustfmt", "clippy"]