.github: Bump iffy/install-nim from 5.0.6 to 5.0.8

Bumps [iffy/install-nim](https://github.com/iffy/install-nim) from 5.0.6 to 5.0.8.
- [Release notes](https://github.com/iffy/install-nim/releases)
- [Changelog](https://github.com/iffy/install-nim/blob/master/CHANGELOG.md)
- [Commits](iffy/install-nim@2546aaf...25e9ede)

---
updated-dependencies:
- dependency-name: iffy/install-nim
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/exercises.yml

@@ -38,7 +38,7 @@ jobs:
 
       - name: Install Nim (non-devel)
         if: matrix.nim != 'devel'
-        uses: iffy/install-nim@2546aaf825947f6bf76be75ff78d74176992e99d
+        uses: iffy/install-nim@25e9ede26d630a40bb8ecb9ce75479e281e717bf
         with:
           version: "binary:${{ matrix.nim }}"
         env:

.github/workflows/uuids.yml

@@ -24,7 +24,7 @@ jobs:
 
     - name: Install Nim
       if: steps.cache-uuids.outputs.cache-hit != 'true'
-      uses: iffy/install-nim@2546aaf825947f6bf76be75ff78d74176992e99d
+      uses: iffy/install-nim@25e9ede26d630a40bb8ecb9ce75479e281e717bf
       with:
         version: "binary:${{ env.NIM_VERSION }}"
       env: