style: fix lints from rust 1.80.0 (#650)

* Also fix doc test markdown errors

Cargo.toml

@@ -11,6 +11,9 @@ repository = "https://github.com/tskit-dev/tskit-rust"
 rust-version = "1.71.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[lints.rust]
+# Added for rust 1.80.0
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(doc_cfg)'] }
 
 [profile.release]
 lto = "fat"

src/table_collection.rs

@@ -83,7 +83,7 @@ impl TableCollection {
     ///
     /// Negative sequence lengths are errors:
     ///
-    /// ```{should_panic}
+    /// ```should_panic
     /// let tables = tskit::TableCollection::new(-55.0).unwrap();
     /// ```
     pub fn new<P: Into<Position>>(sequence_length: P) -> Result<Self, TskitError> {
@@ -1382,10 +1382,10 @@ impl TableCollection {
     /// # Return value
     /// - `Ok(None)`: when truncation leads to empty edge table.
     /// - `Ok(Some(TableCollection))`: when trunction is successfully performed
-    /// and results in non-empty edge table. The table collection is sorted.
+    ///    and results in non-empty edge table. The table collection is sorted.
     /// - `Error(TskitError)`: Any errors from the C API propagate. An
-    /// [TskitError::RangeError] will occur when `intervals` are not
-    /// sorted.
+    ///    [TskitError::RangeError] will occur when `intervals` are not
+    ///    sorted.
     ///
     /// # Notes
     ///

src/trees/treeseq.rs

@@ -220,7 +220,7 @@ impl TreeSequence {
     ///
     /// A `Tree`'s lifetime is tied to that of its tree sequence:
     ///
-    /// ```{compile_fail}
+    /// ```compile_fail
     /// # use streaming_iterator::StreamingIterator;
     /// # use streaming_iterator::DoubleEndedStreamingIterator;
     /// # let mut tables = tskit::TableCollection::new(1000.).unwrap();
@@ -368,10 +368,10 @@ impl TreeSequence {
     /// # Return value
     /// - `Ok(None)`: when truncation leads to empty edge table.
     /// - `Ok(Some(TableCollection))`: when trunction is successfully performed
-    /// and results in non-empty edge table. The tables are sorted.
+    ///    and results in non-empty edge table. The tables are sorted.
     /// - `Error(TskitError)`: Any errors from the C API propagate. An
-    /// [TskitError::RangeError] will occur when `intervals` are not
-    /// sorted.
+    ///    [TskitError::RangeError] will occur when `intervals` are not
+    ///    sorted.
     ///
     /// # Notes
     ///