[Renovate] Update Rust crate git2 to 0.18.1

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
git2	dependencies	patch	0.18.0 -> 0.18.1

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Release Notes

rust-lang/git2-rs (git2)

v0.18.1

Compare Source

0.18.0...0.18.1

Added

• Added FetchOptions::depth to set the depth of a fetch or clone, adding support for shallow clones.
  #​979

Fixed

• Fixed an internal data type (TreeWalkCbData) to not assume it is a transparent type while casting.
  #​989
• Fixed so that DiffPatchidOptions and StashSaveOptions are publicly exported allowing the corresponding APIs to actually be used.
  #​988

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Configuration

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[github-actions]

Filename                               Stmts    Miss  Cover    Missing
-----------------------------------  -------  ------  -------  --------------------------------------
src/application.rs                        46      46  0.00%    103-179
src/cffreference.rs                       70       0  100.00%
src/complain.rs                          106       0  100.00%
src/increment_version.rs                 101      13  87.13%   123-124, 150-155, 234-235, 251-260
src/macros.rs                             17       0  100.00%
src/running.rs                             4       0  100.00%
src/version.rs                            47       0  100.00%
src/graphing/agd.rs                      157       0  100.00%
src/graphing/graph.rs                    144       0  100.00%
src/pattern/buffer.rs                     23       0  100.00%
src/pattern/io_processor.rs               17      17  0.00%    73-160
src/pattern/writer.rs                     75      30  60.00%   134-153, 188-200, 232-260
src/traits/append_as_line.rs               9       0  100.00%
src/traits/colour_message.rs               8       0  100.00%
src/traits/convert_buffer.rs              21       0  100.00%
src/traits/prefer.rs                       3       0  100.00%
src/traits/read_file.rs                   46      34  26.09%   54-55, 69-70, 77-100, 105-122, 133-144
src/traits/rusty_object_notation.rs        9       0  100.00%
src/traits/to_stderr.rs                    4       0  100.00%
src/changelog/comment_changes.rs         159     159  0.00%    107-405
src/changelog/fragment.rs                 55      35  36.36%   99-161
src/changelog/ronlog.rs                  118      72  38.98%   48-239
TOTAL                                   1239     406  67.23%