Make milli use edition 2021 (#4770)

* Make milli use edition 2021

* Add lifetime annotations to milli.

* Run cargo fmt

milli/src/update/index_documents/extract/extract_docid_word_positions.rs

@@ -179,7 +179,7 @@ pub fn extract_docid_word_positions<R: io::Read + io::Seek>(
 
 /// Check if any searchable fields of a document changed.
 fn searchable_fields_changed(
-    obkv: &KvReader<FieldId>,
+    obkv: &KvReader<'_, FieldId>,
     settings_diff: &InnerIndexSettingsDiff,
 ) -> bool {
     let searchable_fields = &settings_diff.new.searchable_fields_ids;
@@ -228,9 +228,9 @@ fn tokenizer_builder<'a>(
 /// Extract words mapped with their positions of a document,
 /// ensuring no Language detection mistakes was made.
 fn lang_safe_tokens_from_document<'a>(
-    obkv: &KvReader<FieldId>,
+    obkv: &KvReader<'_, FieldId>,
     settings: &InnerIndexSettings,
-    tokenizer: &Tokenizer,
+    tokenizer: &Tokenizer<'_>,
     max_positions_per_attributes: u32,
     del_add: DelAdd,
     buffers: &'a mut Buffers,
@@ -295,9 +295,9 @@ fn lang_safe_tokens_from_document<'a>(
 
 /// Extract words mapped with their positions of a document.
 fn tokens_from_document<'a>(
-    obkv: &KvReader<FieldId>,
+    obkv: &KvReader<'a, FieldId>,
     searchable_fields: &[FieldId],
-    tokenizer: &Tokenizer,
+    tokenizer: &Tokenizer<'_>,
     max_positions_per_attributes: u32,
     del_add: DelAdd,
     buffers: &'a mut Buffers,

milli/src/update/index_documents/extract/extract_geo_points.rs

@@ -68,7 +68,7 @@ pub fn extract_geo_points<R: io::Read + io::Seek>(
 
 /// Extract the finite floats lat and lng from two bytes slices.
 fn extract_lat_lng(
-    document: &obkv::KvReader<FieldId>,
+    document: &obkv::KvReader<'_, FieldId>,
     settings: &InnerIndexSettings,
     deladd: DelAdd,
     document_id: impl Fn() -> Value,