fix: ensure correct sourcing of utility files in scripts

- Updated `scripts/generate-changelog.sh` and `scripts/install-git-cliff.sh` to use `SCRIPT_DIR` for sourcing utility files.
- Ensured paths are resolved relative to the script location, independent of the working directory.
- Improved script reliability and portability.

scripts/generate-changelog.sh

@@ -18,8 +18,9 @@
 #   • Generates the changelog; removes a leading empty line.
 set -euo pipefail
 
-source "$(dirname "$0")/../lib/utils.sh"
-source "$(dirname "$0")/../lib/logging.sh"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/../lib/utils.sh"
+source "$SCRIPT_DIR/../lib/logging.sh"
 
 # ───────────────────────────────────────────────
 CONFIG_FILE=""

scripts/install-git-cliff.sh

@@ -14,8 +14,9 @@
 #   • If a specific version was requested, the installed version is compared; identical → exit, different → upgrade.
 set -euo pipefail
 
-source "$(dirname "$0")/../lib/utils.sh"
-source "$(dirname "$0")/../lib/logging.sh"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/../lib/utils.sh"
+source "$SCRIPT_DIR/../lib/logging.sh"
 
 REPO="orhun/git-cliff"