build: Bump MSRV to 1.88

This is necessary to use the let-chains feature in a
follow-up. After upgrading to Rust edition 2024, clippy
wants to collapse various if's with let-chains.

Update image to 20250815-0 since MSRV in Dockerfile is updated.

Signed-off-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
On-behalf-of: SAP philipp.schuster@sap.com

.github/workflows/build.yaml

@@ -15,7 +15,7 @@ jobs:
           - stable
           - beta
           - nightly
-          - "1.87.0"
+          - "1.88.0"
         target:
           - x86_64-unknown-linux-gnu
           - x86_64-unknown-linux-musl

.github/workflows/docker-image.yaml

@@ -41,7 +41,7 @@ jobs:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
           # generate Docker tags based on the following events/attributes
           tags: |
-            type=raw,value=20250807-0
+            type=raw,value=20250815-0
             type=sha
 
       - name: Build and push

.github/workflows/preview-riscv64.yaml

@@ -24,7 +24,7 @@ jobs:
           fetch-depth: 0
 
       - name: Install Rust toolchain
-        run: /opt/scripts/exec-in-qemu.sh rustup default 1.87.0
+        run: /opt/scripts/exec-in-qemu.sh rustup default 1.88.0
 
       - name: Build ${{ matrix.module }} Module (kvm)
         run: /opt/scripts/exec-in-qemu.sh cargo rustc --locked -p ${{ matrix.module }} --no-default-features --features "kvm" -- -D warnings -D clippy::undocumented_unsafe_blocks -W clippy::assertions_on_result_states

.github/workflows/release.yaml

@@ -45,7 +45,7 @@ jobs:
           target: ${{ matrix.platform.target }}
           args: ${{ matrix.platform.args  }}
           strip: true
-          toolchain: "1.87.0"
+          toolchain: "1.88.0"
       - name: Copy Release Binaries
         if: github.event_name == 'create' && github.event.ref_type == 'tag'
         shell: bash