fix build with rustc 1.60.0-nightly (734368a20 2022-02-07)

unreachable!("{}"); is no longer valid, see rust-lang/rust/issues/92137

Author: matthiaskrgr

CHANGELOG.md

@@ -1,8 +1,10 @@
 ## Git
 ```
+Fix build with nightly.
+unreachable!("{}") is no longer accepted: https://github.com/rust-lang/rust/issues/92137
+
 Build: add "ventored-libgit" feature that enables libgit2 vendoring (statically link libgit2 into cargo-cache instead of linking agaist the system libgit2)
 The feature is on by default but it can be skipped (using --no-default-features) by distributors who would like cargo-cache to link against system libgit2
-
 ```
 
 ## Version 0.8.1 (1fcffbb)

src/date.rs

@@ -176,7 +176,7 @@ pub(crate) fn remove_files_by_dates(
         (None, Some(younger)) => AgeRelation::FileYoungerThanDate(younger),
         (Some(older), None) => AgeRelation::FileOlderThanDate(older),
         (Some(_older), Some(_younger)) => {
-            unreachable!("passing both, --remove-if-{older,younger}-than was temporarily disabled!")
+            unreachable!("{}", "passing both, --remove-if-{older,younger}-than was temporarily disabled!")
         } // (Some(older), Some(younger)) => DateComparison::OlderOrYounger(older, younger),
     };