There's a merged pull request on the void-packages repository

libproxy: update to 0.4.18.
https://github.com/void-linux/void-packages/pull/38818

Description:
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#### Testing the changes
- I tested the changes in this PR: **briefly**

Fixes build with gcc12:
```
In file included from /builddir/libproxy-0.4.15/libproxy/extension_config.hpp:24,
                 from /builddir/libproxy-0.4.15/libproxy/proxy.cpp:28:
/builddir/libproxy-0.4.15/libproxy/url.hpp:53:32: error: ISO C++17 does not allow dynamic exception specifications
   53 |         url(const string& url) throw (parse_error);
      |                                ^~~~~
/builddir/libproxy-0.4.15/libproxy/url.hpp:56:36: error: ISO C++17 does not allow dynamic exception specifications
   56 |         url& operator=(string url) throw (parse_error);
      |                                    ^~~~~
/builddir/libproxy-0.4.15/libproxy/extension_config.hpp:34:61: error: ISO C++17 does not allow dynamic exception specifications
   34 |         virtual vector<url>      get_config(const url &dst) throw (runtime_error)=0;
      |                                                             ^~~~~
In file included from /builddir/libproxy-0.4.15/libproxy/proxy.cpp:31:
/builddir/libproxy-0.4.15/libproxy/extension_pacrunner.hpp:44:44: error: ISO C++17 does not allow dynamic exception specifications
   44 |         virtual string run(const url& url) throw (bad_alloc)=0;
      |                                            ^~~~~
/builddir/libproxy-0.4.15/libproxy/extension_pacrunner.hpp:50:63: error: ISO C++17 does not allow dynamic exception specifications
   50 |         virtual pacrunner* get(string pac, const url& pacurl) throw (bad_alloc);
      |                                                               ^~~~~
/builddir/libproxy-0.4.15/libproxy/extension_pacrunner.hpp:58:66: error: ISO C++17 does not allow dynamic exception specifications
   58 |         virtual pacrunner* create(string pac, const url& pacurl) throw (bad_alloc)=0;
      |                                                                  ^~~~~
ninja: build stopped: subcommand failed.
```

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