CI/MSVC: downgrade Rust to 1.82 until cfg(test) is dealt with

See rust-lang/rust#129020

Author: amyspark

ci/test-msvc.bat

@@ -96,7 +96,7 @@ if not exist %HOMEPATH%\.cargo\bin\cargo-cbuild.exe %HOMEPATH%\.cargo\bin\cargo
 
 :: Enable workaround if latest stable Rust caused issues like #968.
 :: Update RUST_DOWNGRADE_VER below as well as required.
-@set DOWNGRADE_RUST_VERSION=0
+@set DOWNGRADE_RUST_VERSION=1
 
 :: now build librsvg
 set PATH=%PATH%;%HOMEPATH%\.cargo\bin
@@ -108,7 +108,7 @@ cd msvc-build
 if exist %INST%\lib\libpcre2-8.a copy /b %INST%\lib\libpcre2-8.a %INST%\lib\pcre2-8.lib
 
 if not "%DOWNGRADE_RUST_VERSION%" == "1" goto :normal_rust_build
-@set RUST_DOWNGRADE_VER=1.77.2
+@set RUST_DOWNGRADE_VER=1.82.0
 %HOMEPATH%\.cargo\bin\rustup install %RUST_DOWNGRADE_VER%-%RUST_HOST%
 meson setup .. --buildtype=release --prefix=%INST_PSX% --pkg-config-path=%INST%\lib\pkgconfig --cmake-prefix-path=%INST% -Dtriplet=%RUST_HOST% -Drustc-version=%RUST_DOWNGRADE_VER% || goto :error
 goto :continue_build