Romans 8, I Corinthians 12, and Galatians 5.
Romans 8: Paul uses the term Spirit of God and Spirit of Christ interchangeably, but as a force of the Father or Jesus, and not as a separate person of the Trinity.
1 Corinthians 12: Paul still uses the term ‘Spirit of God’ to preface the remainder of the verses that he speaks about the Spirit.
Galatians 5: Paul does use the term Spirit as a standalone, yet never indicates that the Spirit is God, rather, the verses indicate what he said in Corinthians and Romans - that the Spirit is a mechanism of Jesus and/or God the Father.
No Trinitarian verses in Paul, I’m afraid.