.github: run tests on go 1.19, 1.20 and 1.21

Sicne we require go v1.19 now at minimum, we cannot run tests on go
v1.17 or v1.18 anymore.

Since there are more recent versions of Go available as well, we start
testing the packages on those versions in addition to 1.19.

.github/workflows/go-getter.yml

@@ -18,10 +18,15 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
+        # Note: while strictly speaking quoting the versions is not necessary
+        # however for versions like 1.10, 1.20, 1.30, etc. without quotes, YAML
+        # renders these versions as floats, so the least-significant 0 gets
+        # dropped from the version number, so those become like 1.1, 1.2, 1.3, etc.
+        # To avoid the issue, we quote them systematically.
         go-version:
-          - 1.17
-          - 1.18
-          - 1.19
+          - "1.19"
+          - "1.20"
+          - "1.21"
         directory:
           - s3
           - gcs
@@ -110,9 +115,9 @@ jobs:
     strategy:
       matrix:
         go-version:
-          - 1.17
-          - 1.18
-          - 1.19
+          - "1.19"
+          - "1.20"
+          - "1.21"
         directory:
           - s3
           - gcs
@@ -190,9 +195,9 @@ jobs:
     strategy:
       matrix:
         go-version:
-          - 1.17
-          - 1.18
-          - 1.19
+          - "1.19"
+          - "1.20"
+          - "1.21"
     permissions:
       id-token: write
       contents: read