.github: bump actions/checkout from 3.4.0 to 3.5.0 (#509)

Links:

- https://github.com/actions/checkout/releases/tag/v3.5.0
- actions/checkout@24cb908...8f4b7f8

.github/workflows/exercises.yml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
       - name: Checkout exercism/nim
-        uses: actions/checkout@24cb9080177205b6e8c946b17badbe402adc938f
+        uses: actions/checkout@8f4b7f84864484a7bf31766abe9204da3cbe65b3
 
       - name: Install Nim (devel)
         if: matrix.nim == 'devel'

.github/workflows/lint-whitespace.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@24cb9080177205b6e8c946b17badbe402adc938f
+        uses: actions/checkout@8f4b7f84864484a7bf31766abe9204da3cbe65b3
 
       - name: Check that every file has no trailing whitespace, and exactly one final newline
         run: ./.github/bin/lint-whitespace

.github/workflows/markdownlint.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@24cb9080177205b6e8c946b17badbe402adc938f
+        uses: actions/checkout@8f4b7f84864484a7bf31766abe9204da3cbe65b3
 
       - name: Run markdownlint
         uses: DavidAnson/markdownlint-cli2-action@5b7c9f74fec47e6b15667b2cc23c63dff11e449e

.github/workflows/shellcheck.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Checkout
-        uses: actions/checkout@24cb9080177205b6e8c946b17badbe402adc938f
+        uses: actions/checkout@8f4b7f84864484a7bf31766abe9204da3cbe65b3
 
       - name: Run shellcheck
         uses: ludeeus/action-shellcheck@00cae500b08a931fb5698e11e79bfbd38e612a38

.github/workflows/uuids.yml

@@ -8,7 +8,7 @@ jobs:
       NIM_VERSION: '1.6.10'
 
     steps:
-    - uses: actions/checkout@24cb9080177205b6e8c946b17badbe402adc938f
+    - uses: actions/checkout@8f4b7f84864484a7bf31766abe9204da3cbe65b3
 
     - name: Get the versions of the installed GCC and OpenSSL
       run: |