Update git2 to compile with latest rustc nightly

This works around the regression in rust-lang/rust#85574

Author: staktrace

src/attr.rs

@@ -69,8 +69,8 @@ impl<'string> AttrValue<'string> {
 ///
 /// Note that this implementation does not differentiate between [`AttrValue::String`] and
 /// [`AttrValue::Bytes`].
-impl PartialEq for AttrValue<'_> {
-    fn eq(&self, other: &AttrValue<'_>) -> bool {
+impl<'string> PartialEq for AttrValue<'string> {
+    fn eq(&self, other: &AttrValue<'string>) -> bool {
         match (self, other) {
             (Self::True, AttrValue::True)
             | (Self::False, AttrValue::False)