ci: fix not committed uv.lock and use uv sync --locked (#637)

# Description

Doing `uv sync` now updates `uv.lock` with `pyjwt` added in #581. Commit
updated file and update CI to fail on inconsistent `uv.lock` via
`--locked`.

Tested via
e6df935:
[failed CI
run](https://github.com/a2aproject/a2a-python/actions/runs/21206882696/job/61005414117?pr=637).

Author: ishymko

.github/workflows/linter.yaml

@@ -23,7 +23,7 @@ jobs:
         run: |
           echo "$HOME/.cargo/bin" >> $GITHUB_PATH
       - name: Install dependencies
-        run: uv sync --dev
+        run: uv sync --locked --dev
 
       - name: Run Ruff Linter
         id: ruff-lint

.github/workflows/unit-tests.yml

@@ -53,7 +53,7 @@ jobs:
         run: |
           echo "$HOME/.cargo/bin" >> $GITHUB_PATH
       - name: Install dependencies
-        run: uv sync --dev --extra all
+        run: uv sync --locked --dev --extra all
       - name: Run tests and check coverage
         run: uv run pytest --cov=a2a --cov-report term --cov-fail-under=88
       - name: Show coverage summary in log

.github/workflows/update-a2a-types.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Configure uv shell
         run: echo "$HOME/.cargo/bin" >> $GITHUB_PATH
       - name: Install dependencies (datamodel-code-generator)
-        run: uv sync
+        run: uv sync --locked
       - name: Define output file variable
         id: vars
         run: |