Add rustup + CHEZ_CONFIGURE_EXTRA to build-jerboa (fix missing rust install)

ober

49dcf3a983a991ab799ac857f8f3889361a00708

diff --git a/.build.yml b/.build.yml
index 476e378..01e7e8a 100644
--- a/.build.yml
+++ b/.build.yml
@@ -36,7 +36,10 @@ tasks:
       # Build the current multicall tool so CI exercises the same
       # jerboa/jerbuild/jpkg image users install.
       cd jerboa
-      make jerboa
+      curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | \
+        sh -s -- -y --profile minimal --default-toolchain 1.94.1
+      source "$HOME/.cargo/env"
+      make jerboa CHEZ_CONFIGURE_EXTRA=--disable-x11
       echo 'export PATH="$HOME/jerboa/dist:$PATH"' >> ~/.buildenv
   - package-code: |
       cd jerboa-code