Bump Docker image to Debian 12 for pure-rust-build

This tests with various additional packages (tools and libraries)
installed whose absence affected the `pure-rust-build` job, to
establish the conditions under which it fails; then bumps the
Debian 10 buster image to Debian 12 bookworm, becuase Debian 10
is past long-term support, and its Docker image is no longer
being updated (see below for details); then redoes the original
tests in reverse order to verify that each combination of
packages had the same effect.

This is several commit squashed together. (The shown reverted
commit hashes may at some point become unavailable on the remote.)

* Temporarily break `pure-rust-build` to verify that it can fail

This makes the `pure-rust-build` CI job attempt to install gitoxide
from `.` with implicit `max`, rather than explicit `max-pure`.

This job, introduced in ed4deac (#624), is intended to identify
unintended C toolchain dependencies. If, without the current
breakage, it is (still) capable of doing this, then as temporarily
modified here, it should fail. If it fails and the error messages
clearly relate to the absence of components necessary to build/use
C libraries, then it is probably (still) working.

Assuming it fails as expected, the Debian version can then be
increased, and then the changes here (and in any follow-up testing
adjustments) undone: if that fails, then succeeds, respectively,
then the job's functionality is most likely preserved across the
upgrade.

* Temporarily add `cmake` to `pure-rust-build` job

This needs to be undone, since `max-pure` definitely should not
require `cmake`. The reason for this temporary change is to figure
out how robust the test is: currently, it fails on `max` as it
should, but reports the absence of `cmake` as the reason. For the
test to be robust, its failure should be for a deeper reason, and
preferably even implicate the `minimal` Rust profile.

* Temporarily add `build-essential` to `pure-rust-build` job

This still installs `gcc` and `libc-dev` because `build-essential`
depends on them, but this als installs packages such as `g++` and
`make`, the absence of which seems to trigger failure before the
effects of installing the `minimal` toolchain do (if they do).

As in the previous change, this will of course need to be undone.

* Temporarily add `pkgconf` and `libssl-dev` to `pure-rust-build` job

This too must of course be undone. Like the last couple temporary
changes, this is to see if the significance of using the `minimal`
Rust toolchain can be identified.

Note: This causes the test to pass, even with the `minimal` Rust
toolchain. That's okay. These effects can be compared to those of
the reverse incremental changes to be made after increasing the
Debian image version.

* Bump Docker image to Debian 12 for `pure-rust-build`

It was previously Debian 10 buster. That version of Debian is past
long term support (LTS), and although third-party Freexian ELTS
updates are publicly available, the image on Docker Hub has not
received any updates since the end of its LTS period. In contrast,
the Debian 11 bullseye and Debian 12 bookworm images continue to be
regularly updated, as of this writing.

* Revert "Temporarily add `pkgconf` and `libssl-dev` to `pure-rust-build` job"

This reverts commit 2ed0a37.

* Revert "Temporarily add `build-essential` to `pure-rust-build` job"

This reverts commit d9e1228.

* Revert "Temporarily add `cmake` to `pure-rust-build` job"

This reverts commit 26ebbe6.

* Revert "Temporarily break `pure-rust-build` to verify that it can fail"

This reverts commit b2e9289.

Author: EliahKagan

.github/workflows/ci.yml

@@ -20,7 +20,7 @@ on:
 jobs:
   pure-rust-build:
     runs-on: ubuntu-latest
-    container: debian:buster
+    container: debian:bookworm
     steps:
       - uses: actions/checkout@v4
       - name: Prerequisites