fix: remove rustc and cargo versions of issue templates

Inspired by what was done in the parent project of `patch-hub`, the `kw`
project, I added the versions of `rustc` and `cargo` in the templates of
the bug report and improvement issues. This does makes sense, but it
sure enough is a hassle to be "mandatory" (the issuer can ignore them,
of course, but it still imposes those).

To make issue reporting more dynamic, remove these fields from the
template.

Signed-off-by: David Tadokoro <[email protected]>

Author: davidbtadokoro

.github/ISSUE_TEMPLATE/bug-report.md

@@ -27,5 +27,3 @@ assignees: ''
 
 - Project branch: [branch name]
 - Project commit hash: [commit hash]
-- `rustc` version: [output of `rustc --version`]
-- `cargo` version: [output of `cargo --version`]

.github/ISSUE_TEMPLATE/code-quality-improvement.md

@@ -19,5 +19,3 @@ assignees: ''
 
 - Project branch: [branch name]
 - Project commit hash: [commit hash]
-- `rustc` version: [output of `rustc --version`]
-- `cargo` version: [output of `cargo --version`]