[backport] [CI] Various CI fixes (#694) (#702)

* [CI] Fix pre-commit failures

* Pin lcov<2.0

Author: chyunsu3

ops/conda_env/dev.yml

@@ -13,7 +13,7 @@ dependencies:
 - coverage
 - codecov
 - ninja
-- lcov
+- lcov<2.0
 - cmake
 - llvm-openmp
 - cython

ops/cpp-python-coverage.sh

@@ -2,9 +2,6 @@
 
 set -euo pipefail
 
-echo "##[section]Installing lcov and Ninja..."
-sudo apt-get install lcov ninja-build
-
 echo "##[section]Building Treelite..."
 mkdir build/
 cd build/