Remove pin on hashlink

`hashlink` `0.9.1` is a member of `rusqlite` `0.31.0`, which uses
`hashbrown`. Previously `hashbrown` broke MSRV on a patch version
(0.14.4), but `hashlink` uses the next minor version of `hashbrown`
(0.15.1) which does adhere MSRV

Author: rustaceanrob

.github/workflows/rust.yml

@@ -45,7 +45,6 @@ jobs:
       - name: Pin packages to allow for MSRV
         if: matrix.msrv
         run: |
-          cargo update -p hashlink --precise "0.8.2" --verbose # hashlink 0.8.3 requires hashbrown 0.14, requiring 1.64.0
           cargo update -p proptest --precise "1.2.0" --verbose # proptest 1.3.0 requires rustc 1.64.0
           cargo update -p regex --precise "1.9.6" --verbose # regex 1.10.0 requires rustc 1.65.0
           cargo update -p home --precise "0.5.5" --verbose # home v0.5.9 requires rustc 1.70 or newer