Revert ".github: Fix Rust version for release to 1.58"

This reverts commit 6a099257e8e9222c53e19fa3858e9211ae943f95.

It is now clear that pinning the toolchain for cross compilation is not
necessary since we only use it for building to aarch64:

https://github.com/rust-lang/rust/issues/95926#issue-1199547707

"This problem doesn't currently show up when cross-compiling from x86_64
to aarch64, since aarch64 doesn't use static-pie by default, but
enabling PIE with -C relocation-model=pie triggers the same bug and
makes the resulting binaries segfault."

Fixes: #3962

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

.github/workflows/release.yaml

@@ -16,12 +16,12 @@ jobs:
       - name: Install Rust toolchain (x86_64-unknown-linux-gnu)
         uses: actions-rs/toolchain@v1
         with:
-            toolchain: 1.58
+            toolchain: stable
             target: x86_64-unknown-linux-gnu
       - name: Install Rust toolchain (x86_64-unknown-linux-musl)
         uses: actions-rs/toolchain@v1
         with:
-            toolchain: 1.58
+            toolchain: stable
             target: x86_64-unknown-linux-musl
       - name: Build
         uses: actions-rs/cargo@v1
@@ -40,7 +40,7 @@ jobs:
       - name: Install Rust toolchain (aarch64-unknown-linux-musl)
         uses: actions-rs/toolchain@v1
         with:
-            toolchain: 1.58
+            toolchain: stable
             target: aarch64-unknown-linux-musl
             override: true
       - name: Static Build (AArch64)