feature: bump minimum required version to 2021.1

[bric3]

This implements the proposed changes in #116

• Removed the old compatibility workarounds.
• Fixed a few compilation warnings (mostly due to deprecation).

[lppedd]

I'll handle the remaining VCS stuff if you want.

idea-conventional-commit/src/main/kotlin/com/github/lppedd/cc/vcs/InternalVcsService.kt

Lines 124 to 128 in 6fa98d2

	@Compatibility(minVersion = "203.4203.26")
	private fun VcsLogProvider.readMetadataComp(
	root: VirtualFile,
	commitsHashes: List<String>,
	): List<VcsCommitMetadata> {

idea-conventional-commit/src/main/kotlin/com/github/lppedd/cc/vcs/InternalVcsService.kt

Lines 185 to 191 in 6fa98d2

	@Compatibility(minVersion = "203.3645.34")
	private fun ensureLogCreated(): Boolean {
	val method =
	VcsProjectLog::class.java.getDeclaredMethod("ensureLogCreated", Project::class.java) // IDEA 203.3645.34+
	?: VcsProjectLog::class.java.getDeclaredMethod("getOrCreateLog", Project::class.java) // IDEA 201.3803.32+
	?: VcsLogContentUtil::class.java.getDeclaredMethod("getOrCreateLog", Project::class.java)
	?: return false

[bric3]

Ah yes missed those, they were not listed in the problem view.

[lppedd]

Generally what I do is search for references to that annotation (I added it just for this reason).
But no worries, I'll do it and test it.

[lppedd]

I'll add commits in this PR.