include/sexp/sexp-error.h: fix missing cstdint include

[juippis]

With gcc-13 and probably clang-16 compilation fails to:

FAILED: CMakeFiles/sexp.dir/src/sexp-error.cpp.o 
/usr/bin/x86_64-pc-linux-gnu-g++  -I/var/tmp/portage/dev-libs/sexp-0.8.3/work/sexp-0.8.3/include  -march=native -O2 -pipe -frecord-gcc-switches -fPIC -Wall -Wextra -Wunreachable-code -Wpointer-arith -Wmissing-declarations -Wno-pedantic -Wno-ignored-qualifiers -Wno-unused-parameter -Wno-missing-field-initializers -MD -MT CMakeFiles/sexp.dir/src/sexp-error.cpp.o -MF CMakeFiles/sexp.dir/src/sexp-error.cpp.o.d -o CMakeFiles/sexp.dir/src/sexp-error.cpp.o -c /var/tmp/portage/dev-libs/sexp-0.8.3/work/sexp-0.8.3/src/sexp-error.cpp
In file included from /var/tmp/portage/dev-libs/sexp-0.8.3/work/sexp-0.8.3/src/sexp-error.cpp:30:
/var/tmp/portage/dev-libs/sexp-0.8.3/work/sexp-0.8.3/include/sexp/sexp-error.h:66:5: error: 'uint32_t' does not name a type
   66 |     uint32_t            get_position(void) const { return position; };
      |     ^~~~~~~~
/var/tmp/portage/dev-libs/sexp-0.8.3/work/sexp-0.8.3/include/sexp/sexp-error.h:34:1: note: 'uint32_t' is defined in header '<cstdint>'; did you forget to '#include <cstdint>'?
   33 | #include <iostream>
  +++ |+#include <cstdint>
   34 | #include <string>

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (8d72207) 99.70% compared to head (082ea07) 99.70%.

:exclamation: Current head 082ea07 differs from pull request most recent head bd1372c. Consider uploading reports for the commit bd1372c to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #31 +/- ## ======================================= Coverage 99.70% 99.70% ======================================= Files 9 9 Lines 668 668 ======================================= Hits 666 666 Misses 2 2 ``` | [Impacted Files](https://app.codecov.io/gh/rnpgp/sexp/pull/31?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=rnpgp) | Coverage Δ | | |---|---|---| | [include/sexp/sexp-error.h](https://app.codecov.io/gh/rnpgp/sexp/pull/31?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=rnpgp#diff-aW5jbHVkZS9zZXhwL3NleHAtZXJyb3IuaA==) | `100.00% <ø> (ø)` | |

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[maxirmx]

LGTM let me bump lts debian version and merge after that

[maxirmx]

Thank you, @juippis

[juippis]

Thank you! And for the quick release too.